Therizinosauria Russell, 1997
Definition- (Therizinosaurus cheloniformis <- Tyrannosaurus rex, Ornithomimus edmontonicus, Mononykus olecranus, Oviraptor philoceratops, Troodon formosus) (Zanno, 2010)
Other definitions- (Alxasaurus elesitaiensis, Enigmosaurus mongoliensis, Erlikosaurus andrewsi, Nanshiungosaurus brevispinus, Segnosaurus galbinensis, Therizinosaurus cheloniformis <- Ornithomimus velox, Troodon formosus, Oviraptor philoceratops) (modified from Russell, 1997)
(Therizinosaurus cheloniformis <- Tyrannosaurus rex, Ornithomimus edmontonicus, Shuvuuia deserti, Oviraptor philoceratops, Troodon formosus) (Sereno, online 2005)
= Segnosauria Barsbold and Perle, 1980
= Segnosaurischia Dong, 1987
= Therizinosauria Sereno, online 2005
Definition- (Therizinosaurus cheloniformis <- Tyrannosaurus rex, Ornithomimus edmontonicus, Shuvuuia deserti, Oviraptor philoceratops, Troodon formosus)
Segnosauria- While therizinosaur taxa were known before the 1980s, Barsbold and Perle (1980) were the first to propose a group greater than family rank for them, using Segnosauria for Segnosaurus, Erlikosaurus and the still unnamed Enigmosaurus. Their only comment on segnosaurs' relationships within theropods was "we presume that Segnosauria took to their particular mode of life, very different from that of other theropods, relatively early" implying an early divergence. Despite describing braincase characters shared with ornithomimosaurs and troodontids, Barsbold (1983) later states "a certain conditionally regarding the segnosaurid condition [within Theropoda] is maintained (Segnosauria); this is possibly a group equivalent to it in rank" and ends up merely saying "that segnosaurids ... should most likely be classified a carnivorous dinosaurs of indefinite systematic position." It was perhaps Barsbold's failure to propose any ideas for their relationship within Theropoda that led workers in the 1980s and early 90s to concentrate on relationships with herbivorous dinosaurs instead. Paul (1984a,b) used manual cladistic analysis to propose segnosaurs were sister to ornithischians, with prosauropods more basal in this Phytodinosauria. Ironically, Paul was also the first to notice the tall astragalar ascending process and fibula backed by the tibia were more similar to Cretaceous theropods than Triassic ones. Gauthier (1986) and Sereno (1989) both also used cladistic methodology, proposing segnosaurs were broad-footed sauropodomorphs (equivalent to modern Plateosauria) or the sister taxon of prosauropods within Sauropodomorpha respectively. Barsbold and Maryanska (1990) noted characters shared with theropods (e.g. "lack of a process of the dentary passing dorsal to the external mandibular fenestra, presence of pleurocoels in the vertebrae, ... expanded pubic foot") and sauropodomorphs, but nonsensically stated "many derived characters of the Segnosauria ... make it impossible to include the segnosaurians among theropods or sauropodomorphs." Despite this, they found Gauthier's hypothesis most probable but in need of further testing. The remains of Alxasaurus were discovered in 1988, and this more basal genus would be the downfall of Segnosauria and the lynchpin for their coelurosaurian identity. Already in 1991 Olshevsky stated "recent work by D. A. Russell (pers. comm.), however, suggests instead that they were very highly derived theropods — as originally classified — and that their resemblance to sauropodomorphs was homoplasious." Russell and Dong's (1994) seminal publication of Alxasaurus confirmed most of Gauthier's proposed saurischian, theropod and tetanurine characters were present in segnosaurs, with several exceptions, and their computerized analysis recovered segnosaurs closest to an oviraptorosaur-troodontid clade, then to ornithomimosaurs. Clark et al. (1994) redescribed Erlikosaurus' skull later that year and noted several characters most similar to ornithomimosaurs, oviraptorosaurs and troodontids among theropods, as well as disputing most character evidence from Paul (1984b) and Sereno (1989). Interestingly, there was not then and has never been a published computerized phylogenetic analysis of dinosaurs including segnosaurs and the proposed characters linking them to various herbivorous dinosaur groups.
Therizinosauroidea to Therizinosauria- Therizinosaurus was originally described as a turtle, but Rozhdestvensky (1970; and possibly as early as Rozhdestvensky and Khozatsky, 1967) used the discovery of Chilantaisaurus to propose the type manual unguals were actually those of a carnosaurian theropod. Only a couple years after the discovery of segnosaurs, Perle (1982) described a hindlimb he referred to Therizinosaurus and noted similarities between that genus and Segnosaurus, proposing therizinosaurids and segnosaurids were closely related within a larger Deinocheirosauria also including Deinocheirus. While the few vague pectoral and forelimb similarities ("very similar" "morphology in the scapulocoracoid region", "the rather specific topography of the superglenoid enlargement ... is the same", "The deltopectoral crest of the humerus was more highly developed ... and, respectively, the flexors M. coracobrachialis and M. humero-radialis were stronger") and uncertain referral of the hindlimb to Therizinosaurus kept the relationship controversial, the hindlimb was recognized as segnosaurian (e.g. Barsbold and Maryanska, 1990). Russell and Dong (1994) confirmed the relationship with the description of Alxasaurus and its pectoral girdle and forelimb, stating "the morphology of the hands and feet thus suggests that Therizinosauridae Maleev, 1954 is a senior synonym for Segnosauridae Perle, 1979." Following this, "Therizinosauridae Maleev 1954 is available for a superfamily containing Alxasaurus and the Therizinosauridae; the group is referred to below as "therizinosauroids."" This publication tends to use the term "segnosaur" as unofficial in quotes, perhaps based on ICZN rules granting a 1954 date to Therizinosauroidea versus Segnosauria's 1980 date, or a wish to distance their tetanurine therizinosauroid concept from the oddball concept of Segnosauria that existed up till that point. Note that priority-wise, while Therizinosauroidea has priority over a potential Segnosauroidea, the ICZN does not regulate names above family level like Segnosauria. So it would have been possible to retain a Segnosauria containing both families, or even containing Therizinosauroidea in the same way Oviraptorosauria contains Caenagnathoidea. In any case, following 1994 the use of Segnosauria in the literature plummeted with Therizinosauroidea being used instead even for more basal examples such as 1999's Beipiaosaurus and 2005's Falcarius. It is ironic then that Russell (1997) proposed Therizinosauria seemingly as a synonym of Therizinosauroidea (without comment or justification) when this certainly lacks priority over Segnosauria. Russell's Therizinosauria was largely ignored over the next decade, and in 2004 Clark et al. happened to provide a node-based definition for Therizinosauroidea which limited it to taxa within the Beipiaosaurus plus Therizinosaurus clade. Zanno's extremely important 2008b thesis on therizinosaurs (published in 2010) followed Clark et al.'s definition "which serves to exclude Falcarius from Therizinosauroidea on the basis of its relatively primitive morphology." With Therizinosauroidea now a subset of therizinosaurs, she followed Russell's usage of Therizinosauria for the stem-group of all therizinosaurs. This has been the consensus through today, finishing the transition from Segnosauria (1980-1993) to Therizinosauroidea (1994-2009) to Therizinosauria (2010+) for this clade.
Segnosaurischia- Segnosaurischia was a group used by Dong to place segnosaurs on an equal rank with Saurischia and Ornithischia, with his 1992 phylogram showing it independently derived from 'thecodonts'. Although Segnosaurischia is often cited as being named by Dong in his 1992 Chinese dinosaur book, there was a 1987 edition which used it first. Dong and Yu (1997) were among the last authors to use the term as by the mid-1990s most experts agreed by then segnosaurs were theropod saurischians.
Phylogenetic position- Placing therizinosaurids with deinocheirids as Perle (1982) and Barsbold (1976) did takes 13 steps in Hartman et al.'s matrix, effectively making Deinocheirus the basalmost therizinosaurian. Making them closer to an oviraptorosaur plus troodontid clade than dromaeosaurids or ornithomimosaurs as in Russell and Dong (1994) takes 35 more steps, so is highly unparsimonious. The pairing of therizinosaurs with oviraptorosaurs, first in Makovicky's (1995a) thesis then published by Holtz (1995) and Makovicky (1995b), was almost universal for the next 15 years but takes 13 more steps. Sereno (1998) placed therizinosaurs sister to ornithomimosaurs, then in 1999 added alvarezsaurids to the analysis and placed these closer to ornithomimosaurs. The former takes 6 steps, while placing them sister to ornithomimosaurs plus alvarezsaurids takes 4 steps. Zanno (2008a,b, 2010) recovered therizinosaurs sister to alvarezsauroids plus pennaraptorans, which takes 6 more steps. Hartman et al. (2019) found therizinosaurs to be sister to alvarezsaurids in basal Maniraptora. Placing therizinosaurs sister to Pennaraptora is only 3 steps longer though, and placing them outside Maniraptoriformes (which has never been recovered in published analyses) is only 6 steps longer.
Therizinosauria defined- Russell (1997) attempted the first definition, which doesn't use any alvarezsauroid as an external specifier so would fail in Hartman et al.'s topology where alvarezsauroids and therizinosaurs are sister taxa. It's also inefficient in using five additional therizinosaurs as internal specifiers when only the eponymous taxon is needed. Zanno (2010) published a variant of Sereno's (online, 2005) definition, with the useless change of switching Shuvuuia with Mononykus. It is used here although the inclusion of Tyrannosaurus hasn't been neccessary for any proposed phylogeny. If anything, I might suggest using Plateosaurus and Stegosaurus as additional specifiers instead, just to ensure views like Paul's (1984, 1988a,b) and Sereno's (1989) are covered.
Ex-therizinosaurs- Russell (1984) referred a supposed astragalus (AMNH 5027) from the Hell Creek Formation of Montana, US to Therizinosauridae indet.. Russell and Manabe (2002) revealed this was the element properly identified as a Tyrannosaurus quadrate by Carpenter (1992).
Sues (1978) identified frontal CMN 12349 as Dromaeosaurus and frontal CMN 12355 as Theropoda indet., although note his plates 7 and 8 are switched so that they are given each others' captions. Currie (1987) accepted CMN 12349 as Dromaeosaurus, but with regard to CMN 12355 stated that "comparison with Mongolian specimens suggests that it may represent Erlicosaurus (Currie, in preparation)." Currie (1992) again stated CMN 12355 "may represent the segnosaurid Erlicosaurus" (although note that as in Sues' paper it is mislabeled 12349 in his Figure 2) and also referred TMP 1981.016.0231 to Segnosauridae. Currie (2005) listed CMN 12349 as a tentative "therizinosauroid similar to Erlikosaurus", but figured CMN 12355 so probably meant that specimen. Indeed, it seems CMN 12349 was correctly identified as Dromaeosaurus in the first place as it is similar to the holotype and has only been referred to Therizinosauroidea accidentally due to Sues' original plate caption mistake. Larson et al. (2014) performed a morphometric analysis of Dinosaur Park coelurosaur frontals, and found that CMN 12355 grouped with Troodon, so is troodontid instead. Yet without including a therizinosaur such as Erlikosaurus itself, the study only had so much explanatory power. More recently, Cullen et al. (2020) expanded the analysis to include both Erlikosaurus and the Bissekty therizinosaurid, still recovering CMN 12355 within the Dinosaur Park troodontid range and far from therizinosaurids. Both it and the less complete TMP 1981.016.0231 are here referred to Troodon formosus sensu lato.
Mateer (1987) described a pedal ungual which Nessov (1995) referred it to Therizinosauria or "groups most closely related to them" (which in his opinion consisted of spinosaurids and dryptosaurids). Provisional comparisons suggest it more closely resembles pedal unguals of Sinraptor and Poekilopleuron than those of any therizinosaurs (e.g. Beipiaosaurus, Alxasaurus, Nothronychus, Erlikosaurus), which tend to be deeper and more curved. CCMGE 456/12457 was figured as a segnosaur by Nessov but reassigned to Dromaeosauridae by Sues and Averianov (2014).
A distal phalanx was discovered in 1931 and referred to Theropoda indet. by Riabinin (1937), but referred to Therizinosauridae based on the unequally deep collateral ligament pits by Averianov et al. (2003). Zanno (2008b) noted both sides having well defined pits (albeit better developed on one side) is unlike therizinosaurs.
Currie (1992) described TMP 1979.015.0001 from the Dinosaur Park Formation of Alberta, Canada as a possible segnosaurid pedal ungual. Ryan and Russell (2001) listed cervical vertebra TMP 1986.207.0017 from the Scollard Formation of Alberta, Canada as Segnosauridae indet. in their faunal list. Cullen et al. (2020) found both specimens "to be most similar in morphology to caenagnathids."
Curtice (2000) reports that "In 1997 at the DinoFest 2 symposium Ratkevich suggested the specimen was a therizinosaur (McCord, personal communication, 1999)", referring to the sauropod Sonorasaurus.
AMNH 21597 is figured as therizinosaurid ungual on the AMNH online catalog, but the low curvature and distally placed flexor tubercle are instead almost identical to Archaeornithomimus (e.g. AMNH 6570, 6576).
References- Riabin, 1937. A new discovery of dinosaurs in Transbaikalia. Ezhegodnik Vsesoyuznogo Paleontologicheskogo Obshchestva. 11, 141-144.
Rozhdestvensky and Khozatsky, 1967. Late Mesozoic terrestrial vertebrates of the Asian part of the USSR. Stratigraphy and Paleontology of Mesozoic and Paleogene-Neogene Continental Beds of the Asian Part of the USSR. Nauka, Leningrad. 82-92.
Rozhdestvensky, 1970. Giant claws of enigmatic Mesozoic reptiles. Paleontological Journal. 1970(1), 131-141.
Sues, 1978. A new small theropod dinosaur from the Judith River Formation (Campanian) of Alberta, Canada. Zoological Journal of the Linnaean Society of London. 62, 381-400.
Barsbold and Perle, 1980. Segnosauria, a new infraorder of carnivorous dinosaurs. Acta Palaeontologica Polonica. 25(2), 187-195.
Perle, 1982. On a new finding of the hindlimb of Therizinosaurus sp. from the Late Cretaceous of Mongolia. Problems in Mongolian Geology. 5, 94-98.
Paul, 1984a. The archosaurs: A phylogenetic study. Third Symposium on Mesozoic Terrestrial Ecosystems, Short Papers. 175-180.
Paul. 1984b. The segnosaurian dinosaurs: Relics of the prosauropod-ornithischian transition? Journal of Vertebrate Paleontology. 4(4), 507-515.
Russell, 1984. A checklist of the families and genera of North American dinosaurs. National Museum of Natural Science, National Museums of Canada, Syllogeus. 53, 1-35.
Gauthier, 1986. Saurischian monophyly and the origin of birds. Memoirs of the Californian Academy of Sciences 8, 1-55.
Currie, 1987. Theropods of the Judith River Formation of Dinosaur Frovincial Park, Alberta. In Currie and Koster (eds). 4th Symposium of Mesozoic Terrestrial Ecosystems Short Papers. Tyrell Museum of Palaeontology, Drumheller, Alberta. 52-60.
Dong, 1987. Dinosaurs from China. China Ocean Press, Beijing. 114 pp.
Mateer, 1987. A new report of a theropod dinosaur from South Africa. Palaeontology. 30(1), 141-145.
Paul, 1988. Predatory Dinosaurs of the World. Simon & Schuster: New York 464 pp.
Sereno, 1989. Prosauropod monophyly and basal sauropodomorph phylogeny. Journal of Vertebrate Paleontology. 9(3),38A.
Barsbold and Maryanska, 1990. Saurischia sedis mutabilis: Segnosauria. In Weishampel, Dodson and Osmolska (eds.). The Dinosauria. University of California Press. 408-415.
Olshevsky, 1991. A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings. 2, 196 pp.
Carpenter, 1992. Tyrannosaurids (Dinosauria) of Asia and North America. In Mateer and Chen (eds.). Aspects of nonmarine Cretaceous geology. Beijing, China: Ocean Press. 250-268.
Currie, 1992. Saurischian dinosaurs of the Late Cretaceous of Asia and North America. In Mateer and Chen (eds.). Aspects of Nonmarine Cretaceous Geology. China Ocean Press. 237-249.
Dong, 1992. Dinosaurian Faunas of China. China Ocean Press, Beijing. 188 pp.
Clark, Perle and Norell, 1994. The skull of Erlicosaurus andrewsi, a Late Cretaceous "segnosaur" (Theropoda: Therizinosauridae) from Mongolia. American Museum Noviates. 3115, 39 pp.
Russell and Dong, 1994. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences. 30(10), 2107-2127.
Holtz, 1995. A new phylogeny of the Theropoda. Journal of Vertebrate Paleontology. 15(3), 35A.
Makovicky, 1995a. Phylogenetic aspects of coelurosaurian vertebral morphology. Journal of Vertebrate Paleontology. 15(3), 43A.
Makovicky, 1995b. Phylogenetic aspects of the vertebral morphology of Coelurosauria (Dinosauria: Theropoda). Masters thesis, Copenhagen University, Copenhagen.[pp]
Nessov, 1995. Dinosaurs of nothern Eurasia: New data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.
Russell, 1997. Therizinosauria. In Currie and Padian (eds.). Encyclopedia of Dinosaurs. 729-730.
Sereno, 1998. A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen. 210(1), 41-83.
Sereno, 1999. The evolution of dinosaurs. Science. 284, 2137-2147.
Curtice, 2000. The axial skeleton of Sonorasaurus thompsoni Ratkevitch 1998. Proceedings of the Southwest Paleontological Symposium. 7, 83-87.
Ryan and Russell, 2001. Dinosaurs of Alberta (exclusive of Aves). in Tanke and Carpenter (eds). Mesozoic Vertebrate Life. Indiana University Press. 279-297.
Russell and Manabe, 2002. Synopsis of the Hell Creek (uppermost Cretaceous) dinosaur assemblage. In Hartman, Johnson and Nichols (eds.). The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern Great Plains: An integrated continental record of the end of the Cretaceous. Geological Society of America Special Paper. 361, 169-176.
Averianov, Starkov and Skutschas, 2003. Dinosaurs from the Early Cretaceous Murtoi Formation in Buryatia, Eastern Russia. Journal of Vertebrate Paleontology. 23(3), 586-594.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. in In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Currie, 2005. Theropods, including birds. In Currie and Koppelhus (eds.). Dinosaur Provincial Park, a spectacular ecosystem revealed. Part Two, Flora and Fauna from the park. Indiana University Press. 367-397.
Sereno, online 2005. Stem Archosauria - TaxonSearch. http://www.taxonsearch.org/dev/file_home.php [version 1.0, 2005 November 7]
Zanno, 2008a. The phylogeny of Therizinosauria (Theropoda: Maniraptora): Implications for the evolution of coelurosaurs. Journal of Vertebrate Paleontology. 28(3), 164A.
Zanno, 2008b. A taxonomic and phylogenetic reevaluation of Therizinosauria (Dinosauria: Theropoda): Implications for the evolution of Maniraptora. PhD Thesis. The University of Utah. 329 pp.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Larson, Cullen, Todd and Evans, 2014. Geometric morphometrics of small theropod frontals from the Dinosaur Park Formation, Alberta. Journal of Vertebrate Paleontology. Program and Abstracts 2014, 165.
Sues and Averianov, 2014. Dromaeosauridae (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan and the phylogenetic position of Itemirus medullaris Kurzanov, 1976. Cretaceous Research. 51, 225-240.
Button, Zanno, You and Kirkland, 2015. Dichotomous evolution of tooth growth and replacement strategies in herbivorous dinosaurs. Journal of Vertebrate Paleontology. Program and Abstracts 2015, 100.
King, 2015. Morphometric analysis of semicircular canals in Therizinosauria (Theropoda: Maniraptora) with implications for endocranial modification during a trophic shift. Journal of Vertebrate Paleontology. Program and Abstracts 2015, 154.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247
Cullen, Larson, Zanno, Currie and Evans, 2020. Theropod biodiversity patterns in the Dinosaur Park Formation (Late Cretaceous: Campanian) of Alberta revealed through morphometrics and biostratigraphy. The Society of Vertebrate Paleontology 80th Annual Meeting, Conference Program. 115.

Martharaptor Senter, Kirkland and DeBlieux, 2012
M. greenriverensis Senter, Kirkland and DeBlieux, 2012
Barremian, Early Cretaceous
Yellow Cat Member of Cedar Mountain Formation, Utah, US
Holotype- (UMNH VP 21400) cervical neural arch fragment, first dorsal centrum (62.1 mm), incomplete distal caudal centrum, incomplete scapula, distal radius, partial ulna, distal metacarpal I, proximal phalanx I-1, distal phalanx I-1, manual unguals I (one fragmentary), distal phalanx II-1(?), distal phalanx II-2, manual unguals II, distal phalanx III-?, manual unguals III, distal pubis(?), proximal ischium, metatarsal I, incomplete pedal ungual I, proximal metatarsal II, distal metatarsal II, proximal metatarsal III, distal metatarsal IV, incomplete phalanx IV-?, three proximal phalanges II/IV-1, two proximal pedal phalanges, three distal pedal phalanges, proximal pedal ungual, fragments
Diagnosis- (after Senter et al., 2012) cervical prezygapophyses not flexed; anterior dorsal vertebrae with hypapophyses and a single pair of pleurocoels; distal end of scapula expanded; manual unguals without proximodorsal lips and with prominent flexor tubercles and strong curvature; manual unguals in which total length perpendicular to the articular facet is subequal to total height parallel to the articular facet; ungual of manual digit III nearly as large as that of digit II; proximal end of ischium laterally compressed; metatarsal I proximally attenuated and distally reduced in transverse width relative to the other metatarsals; all metatarsals distally non-ginglymoid; fourth metatarsal distally attenuated immediately proximal to condyles; pedal unguals laterally compressed and strongly curved; first pedal ungual smaller than the others.
Comments- Senter et al. (2012) found this to be a basal therizinosauroid between Beipiaosaurus and Alxasaurus using his version of the TWiG matrix. Similarly, Hartman et al. (2019) recovered it as a therizinosaurian excluded from the Alxasaurus+Segnosaurus clade.
References- Senter, Kirkland, Deblieux and Madsen, 2010. Three new theropods from the Cedar Mountain Formation (Lower Cretaceous) of Utah. Journal of Vertebrate Paleontology. Program and Abstracts 2010, 162A.
Senter, Kirkland and DeBlieux, 2012. Martharaptor greenriverensis, a new theropod dinosaur from the Lower Cretaceous of Utah. PLoS ONE. 7(8), e43911.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247

"Tiantaiosaurus" Qian, 2011
"T. sifengensis" Qian, 2011
Late Aptian, Early Cretaceous
Laijia Formation, Zhejiang, China
Material- (~5.5 m) twelve cervical vertebrae, nine dorsal vertebrae, thirteen incomplete dorsal ribs, twenty-eight caudal vertebrae, incomplete ilium, incomplete pubis, distal ischium, distal femur, tibia, astragalus
Comments- The genus was spelled "Tiantaisaurus" by Qian et al. (2012), which Zheng (pers. comm. to Creisler, DML 2016) indicates Dong wanted to name it. Discovered in 2005, Qian et al. state Dong, Chen and Jiang wrote a manuscript describing it in 2007, but that it had not been officially published. Thus citations to "Dong et al., 2007" after the name are incorrect. The material has been mounted as of 2006 however. The name is a nomen nudum due to being said to be unofficial (ICZN Article 8.3), not having a listed holotype (Article 16.4), and not being explicitly cited as gen. et sp. nov. (Article 16.1). Among the pertinent notes, Qian et al. state at least one cervical is missing (atlas?), cervicals 7-8 are the longest at twice dorsal length, cervicals are pneumatic with amphiplatyan centra, dorsals also have flat ends, and the pubes and ischia lack distal fusion.
References- Qian, 2011. Chinese dinosaur spectrum (60) - [Shifeng Tiantai dragon] (Tiantaiosaurus sifengensis Dong, et al, 2007). Journal of Geology. 35(4), 385.
Qian, Zhang, Jiang, Jiang, Zhang, Chen and Xing, 2012. Cretaceous therizinosaurs in Zhejiang of eastern China. Journal of Geology. 36(4), 337-348.
Creisler, DML 2016. https://web.archive.org/web/20200712114222/http://dml.cmnh.org/2016Jan/msg00088.html

undescribed Therizinosauria (Dmitriev, 1960)
Late Barremian-Mid Aptian, Early Cretaceous
Mogoito Member of Murtoi Formation, Russia
Material- (ZIN PH 2/13) proximal pedal ungual (Averianov et al., 2003)
(lost) manual ungual II (Dmitriev, 1960)
manual ungual (Starkov pers. comm. to Nessov, 1995)
Comments- Dmitriev (1960) described a large theropod manual ungual found in 1959, which was later referred to Carnosauria by Rozhdestvensky (1970). Nessov (1995) noted Rozhdestvensky's specimen was a possible therizinosaur and remarked on another similar specimen. Averianov et al. (2003) confirmed the therizinosaurian identity for Dmitriev's specimen and an additional partial pedal ungual they describe and illustrate.
References- Dmitriev, 1960. New findings of dinosaurs in Buryatia. Paleontologicheskii Zhurnal. 1, 148.
Rozhdestvensky, 1970. Giant claws of enigmatic Mesozoic reptiles. Paleontological Journal. 1970(1), 131-141.
Nessov, 1995. Dinosaurs of nothern Eurasia: new data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.
Averianov, Starkov and Skutschas, 2003. Dinosaurs from the Early Cretaceous Murtoi Formation in Buryatia, Eastern Russia. Journal of Vertebrate Paleontology. 23(3), 586-594

undescribed therizinosaur (Nessov, 1995)
Mid Albian, Early Cretaceous
Lower Khodzhakul Formation, Uzbekistan
Material- ungual
Reference- Nessov, 1995. Dinosaurs of nothern Eurasia: new data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.

undescribed Therizinosauria (Nessov, 1995)
Early Cenomanian, Late Cretaceous
Upper Khodzhakul Formation, Uzbekistan
Material- (CCMGE 457/12457) manual ungual
(ZIN PH 33/16) proximal humerus (Sues and Averianov, 2015)
(ZIN PH 1157/16) tooth (Sues and Averianov, 2015)
few teeth, humeral fragments (Sues and Averianov, 2015)
Comments- Sues and Averianov (2015) found the Khodzhakul therizinosauroid did not differ from the Bissekty taxa in preserved materials.
Reference- Nessov, 1995. Dinosaurs of nothern Eurasia: new data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.
Sues and Averianov, 2015. Therizinosauroidea (Dinosauria: Theropoda) from the Upper Cretaceous of Uzbekistan. Cretaceous Research. 59, 155-178.

undescribed therizinosaur (Sues and Averianov, 2015)
Late Turonian-Coniacian, Late Cretaceous
Aitym Formation, Uzbekistan
Material- fragmentary coracoid
Reference- Sues and Averianov, 2015. Therizinosauroidea (Dinosauria: Theropoda) from the Upper Cretaceous of Uzbekistan. Cretaceous Research. 59, 155-178.

undescribed possible therizinosaur (Nessov, 1995)
Santonian, Late Cretaceous
Syuk Syuk Formation, Kazakhstan
Material- unguals
Comments- This is based on unguals tentatively referred to Alectrosaurus by Prinada (1925, 1927) and/or Riabinin (1938), since the well known unguals originally referred to Alectrosaurus by Gilmore are therizinosaurian.
References- Prinada, 1925. Search for remains of large vertebrates of Upper Cretaceous age in Turkestan. Report on the state of activities of the Geological Committee for 1924. Part II, III. Izvyestiya Gyeologichyeskogo komityeta. 44(2), 257.
Prinada, 1927. Report on the excavation at the localities where dinosaur bones were discovered. Report on the state of activities of the Geological Committee for 1925. Part II, III. Izvyestiya Gyeologichyeskogo komityeta. 45(4), 453-454.
Riabinin, 1938. Some results of the study of the Upper Cretaceous dinosaur fauna from the vicinity of st. Sary-Agachin, Southern Kazakhstan. Problyemy palyeontologii. 4, 125-135.
Nessov, 1995. Dinosaurs of nothern Eurasia: new data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.

undescribed possible therizinosaur (Carpenter, 2009 online)
Late Albian, Early Cretaceous
Mussentuchit Member of the Cedar Mountain Formation, Utah, US
Material- few teeth
Comments- Carpenter (online 2009) notes "A therizinosaurid may also be present in the Mussentuchit based on a few teeth."
Reference-Carpenter, 2009 online. https://web.archive.org/web/20090517064058/http://scientists.dmns.org/kenCarpenter/cedar%2Dmountain%2Dproject/dinosaurs%2Dof%2Dthe%2Dcedar%2Dmountain%2Dformation/

undescribed therizinosaur (Manning, Joysey and Cruikshank, 1997)
Santonian-Campanian, Late Cretaceous
Nanchao Formation, Henan, China
Material- embryos, eggs
Description- This belongs to the oospecies Macroelongatoolithus xixiaensis. The eggs are elongate, unlike the dendroolithid therizinosaur eggs.
Reference- Manning, Joysey and Cruikshank, 1997. Observations of microstructures within dinosaur eggs from Henan Province, Peoples Republic of China. in Wolberg, Stump and Rosenburg eds. Dinofest International: Proceedings of a Symposium held at Arizona State University. Philadelphia: Academy of Sciences. 287-290.

unnamed possible therizinosaur (Young, 1958)
Campanian, Late Cretaceous
Wangshi Group, Shandong, China
Material- ungual
Comments- Described as a carnosaur by Young (1958), but identified as a probable segnosaur by Nessov (1995).
References- Young, 1958.
Nessov, 1995. Dinosaurs of nothern Eurasia: new data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.

undescribed therizinosaur (Long, 1992)
Late Maastrichtian, Late Cretaceous
Miria Formation, Western Australia, Australia
Material- proximal humerus (~350 mm)
Reference- Long, 1992. First dinosaur bones from Western Australia. The Beagle, Records of the Northern Territory Museum of Arts and Sciences. 9, 21-28.

unnamed possible therizinosaur (Rauhut, 1999)
Cenomanian, Late Cretaceous
Wadi Milk Formation, Sudan
Material- (Vb-839) incomplete pedal ungual (~50 mm)
Comments- Rauhut believes this is a manual ungual and places it in the Coelurosauria based on its proximodorsal lip, but a lip is variably present thropughout Avetheropoda. This ungual has several strange characters, but of described manual unguals resembles Elmisaurus' the most. It differs from the latter in being shallower, being wider proximally, having a wider proximodorsal lip, a slightly more proximally placed flexor tubercle that is less separated from the ventral articular lip, a groove ventrally distal to the flexor tubercle, artery grooves that run dorsodistally to join ~1/3 down the ungual, and a more concave articular surface with no central ridge. The ventral groove, lack of a central proximal ridge and artery groove arrangement are unique among described manual unguals. Elmisaurus is said to have a very indistinctly divided articular surface however, and even that is only present in the ventral portion. The broad proximal surface and lack of a central proximal ridge are more similar to a pedal ungual, but the prominent rounded flexor tubercle, proximodorsal lip and narrow main body are not. Some dromaeosaurs (Saurornitholestes, Achillobator, Sudanese taxon) have pedal unguals with such flexor tubercles (on their second digits), and these have especially distinct central proximal ridges, slender proximal ends and sharp ventral edges. These and therizinosaurs have narrow main bodies on their pedal claws. Among therizinosaurs, it resembles "Chilantaisaurus" zheziangensis the most, especially in the slight proximodorsal lip and prominent flexor tubercle. Additionally, the proximal outline is similar to Nothronychus. I provisionally consider this a therizinosaur pedal ungual, the priminent proximodorsal lip and dorsally angled artery grooves indicate a diagnosable taxon.
Reference- Rauhut, 1999. A dinosaur fauna from the Late Cretaceous (Cenomanian) of Northern Sudan. Palaeontologia Africana. 35, 61-84.

undescribed therizinosaur (Zanno, 2010)
Barremian, Early Cretaceous
Yellow Cat Member of Cedar Mountain Formation, Utah, US
Material- (CEUM 52399) pedal phalanx IV-2
(CEUM 53282) pedal phalanx III-2
(CEUM coll.) (at least 25 individuals; some adult) hundreds of elements including lacrimal, jugal, frontal, postorbital, quadrate, dentary, vertebrae, ilium, pubis, femora (to 400 mm)
Comments- Zanno (2010a,b) noted these materials from the Suarez Quarry differ from the Falcarius type locality in vertebral and pelvic characters, but pending further preparation and study could merely be different due to ontogenetic and/or individual variation. Zanno et al. (2014) later revised this interpretation, finding that maximum femoral length and length distribution is similar in both quarries, and that histological analyses show individuals of comparable age groups are present in both. They proposed the Suarez taxon is more derived than Falcarius due to- mandibular condyles of quadrate highly displaced ventrally; "relatively straight and acuminate symphyseal aspect of the dentary"; reduced dentary tooth recurvature; ilium with higher preacetabular process; pubic boot larger, >50% of pubic length. The taxon is also apparently troodontid-like in some characters, and the authors note that the Geminiraptor type maxilla is from the same quarry, where no other troodontid material has been recovered.
References- Zanno, 2010a. Osteology of Falcarius utahensis: Characterizing the anatomy of basal therizinosaurs. Zoological Journal of the Linnaean Society. 158, 196-230.
Zanno, 2010b. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Zanno, Kirkland and Herzog, 2014. Second therizinosaurian mass death locality in the Lower Cretaceous Cedar Mountain Formation yields a new taxon. Journal of Vertebrate Paleontology. Program and Abstracts 2014, 260.

undescribed therizinosaur (Kobayashi et al., 2013)
Late Cretaceous
Javkhlant Formation, Mongolia
Material- seventeen egg clutches (510x430 mm; eggs 130 mm in diameter)
Comments- The eggs are dendroolithid, prompting the authors to refer them to therizinosauroids.
Reference- Kobayashi, Lee, Barsbold, Zelenitsky and Tanaka, 2013. First record of a dinosaur nesting colony from Mongolia reveals nesting behavior of therizinosauroids. Journal of Vertebrate Paleontology. Program and Abstracts 2013, 155.

Thecocoelurus Huene, 1923
T. daviesi (Seeley, 1888) Huene, 1923
= Thecospondylus daviesi Seeley, 1888
= Coelurus daviesi (Seeley, 1888) Nopsca, 1901
Barremian, Early Cretaceous
Wessex Formation, England
Holotype- (NHMUK R181) partial posterior cervical vertebra (~68 mm)
Comments- After a long history as a generic small theropod, Naish et al. (2001) and Naish and Martill (2002) identified Thecocoelurus as an enigmosaur based on the ventrally hourglass-shaped centrum with ventrolateral ridges joining the parapophyses, and as an oviraptorosaur based on the round pneumatic foramina and gracile neural spine. However, Kirkland et al. (2004) later noted strong similarities with their new basal therizinosaur Falcarius, suggesting placement in this clade instead. Indeed, Zanno (2010) found Falcarius has both of the supposed oviraptorosaurian characters, and Jianchangosaurus does as well. However, Naish (online, 2007) has suggested Thecocoelurus isn't a therizinosaur after all (citing Naish and Martill, in press). Naish later (2011) noted Noasaurus has the enigmosaurian central morphology, and shares the low neural spine and U-shaped prezygapophyseal gap with these taxa and Thecocoelurus as well (though note Naish and Martill believed the latter was too broken to code for gap shape). As Naish found the Early Cretaceous age and European location more congruent with abelisauroids than caenagnathids, he tentatively referred Thecocoelurus to Neoceratosauria/Abelisauroidea. Most recently, Allain et al. (2014) believed Thecocoelurus was identical in form to their new supposed Angeac ornithomimosaur. They distinguished both from Noasaurus based on their concave anterior central surface, but this is true in Masiakasaurus as well. They also paired Thecocoelurus with the Angeac taxon based on pneumatic foramina above the prezygapophyses which invade the neural arch. Yet these are present in cervicals 6-10 of Masiakasaurus, at least cervical 9 of Heyuannia, and in Conchoraptor and "Ingenia". They are also only present on the left side of Thecocoelurus, placed more posteriorly than in at least Masiakasaurus and the Angeac taxon, perhaps suggesting breakage of a naturally hollow area or pneumatic asymmetry. The only preserved posterior cervical of Falcarius doesn't preserve this area, nor does the illustrated cervical of Chirostenotes.
Comparisons- Given the diversity of proposed relatives, a detailed comparison is in order. Contra Naish and Martill, the specimen resembles posterior cervicals more than anterior ones, and indeed the supposedly identical Angeac vertebra matches the seventh or eighth of Harpymimus based on elongation, central articular surface orientation, prezygapophyseal length and orientation, etc. (contra Allain et al., 2014). The elongate parapophyses resemble Falcarius, Chirostenotes and Similicaudipteryx more than Masiakasaurus or the Angeac taxon. The anterior pleurocoels are placed in an obvious fossa, like Falcarius and the Angeac taxon, but unlike Masiakasaurus, Chirostenotes or Similicaudipteryx. The infradiapophyseal fossa is developed as an elongate groove, as in Falcarius but unlike Masiakasaurus, the Angeac taxon, Chirostenotes or Similicaudipteryx. The centrum is taller than wide (midline height / width minus parapophyses 133%) as in Falcarius (118%), but unlike the Angeac taxon (95%) and especially Chirostenotes (74%) and Masiakasaurus (64%). The anterior peduncular fossae are well defined as in Chirostenotes and at least anterior Falcarius cervicals, but unlike Masiakasaurus or the Angeac taxon. They are also placed far below the diagonal prezygapophyseal surface as in at least anterior Falcarius cervicals, but unlike the Angeac taxon, Chirostenotes or Masiakasaurus. These two characters are found in Masiakasaurus anterior cervicals too though, so the resemblence to Falcarius anterior cervicals may not be important. The prespinal fossa is broad like Chirostenotes and Masiakasaurus but unlike the Angeac taxon. It has anteroposteriorly broad exposure dorsally as in the Angeac taxon and at least anterior Falcarius cervicals, but not Masiakasaurus (including anterior cervicals of the latter).
Overall, Thecocoelurus is most similar to Falcarius and least similar to Masiakasaurus. There are four good characters shared with Falcarius to the exclusion of the Angeac taxon, and three characters that are more similar to Chirostenotes than to the Angeac taxon, but two characters that are more similar to the Angeac taxon than to Chirostenotes. Falcarius does differ from Thecocoelurus in having a ventral median ridge on its centra, but this is an autapomorphy not seen in other therizinosaurs. Besides this, no characters differ between the specimen except exact size and shape of pneumatic features, which themselves vary between right and left sides of Thecocoelurus. Both are Barremian, and Thecocoelurus is 58% the size of the Falcarius individual that preserved the posterior cervical (though a growth series is known, where that individual falls is unreported). Whether Thecocoelurus and Falcarius share derived characters to the exclusion of other therizinosaurs would require more study, but at the moment is seems most parsimonious to consider Thecocoelurus a basal therizinosaur and not closely related to oviraptorosaurs, the Angeac taxon or noasaurids.
References- Seeley, 1888. On Thecospondylus daviesi (Seeley), with some remarks on the classification of the Dinosauria. Quarterly Journal of the Geological Society, London. 44, 79-86.
Nopcsa, 1901. Synopsis und Abstammung der Dinosaurier. Foldt. Kozl. 31, 247-288.
Huene, 1923. Carnivorous Saurischia in Europe since the Triassic. Bulletin of the Geological Society of America. 34, 449-458.
Naish, 1999. Studies on Wealden Group theropods – an investigation into the historical taxonomy and phylogenetic affinities of new and previously neglected specimens. MPhil thesis, University of Portsmouth.
Naish, Hutt and Martill, 2001. Saurichian dinosaurs 2: theropods. in Martill and Naish (eds). Dinosaurs of the Isle of Wight. The Palaeontological Association. 242-309.
Naish and Martill, 2002. A reappraisal of Thecocoelurus daviesi (Dinosauria: Theropoda) from the Early Cretaceous of the Isle of Wight. Proceedings of the Geologists’ Association. 113, 23-30.
Kirkland, Zanno, DeBlieux, Smith and Sampson, 2004. A new, basal-most therizinosauroid (Theropoda: Maniraptora) from Utah demonstrates a Pan-Laurasian distribution for Early Cretaceous therizinosauroids. Journal of Vertebrate Paleontology. 24(3), 25-26.
Naish, online 2007. https://web.archive.org/web/20090212202320/https://scienceblogs.com/tetrapodzoology/2007/02/therizinosauroids_and_altanger.php
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Naish, 2011. Theropod dinosaurs. In Batten (ed.). English Wealden Fossils. The Palaeontological Association. 526-559.
Allain, Vullo, Le Loeuff and Tournepiche, 2014. European ornithomimosaurs (Dinosauria, Theropoda): An undetected record. Geologica Acta. 12(2), 127-135.
Naish and Martill, in press.

Falcarius Kirkland, Zanno, Sampson, Clark and DeBlieux, 2005
F. utahensis Kirkland, Zanno, Sampson, Clark and DeBlieux, 2005
Barremian, Early Cretaceous
Yellow Cat Member of Cedar Mountain Formation, Utah, US
Holotype- (UMNH VP 15000) (subadult) incomplete braincase
Paratypes- (UMNH VP 12283, 12285, 12286, 12288, 12290, 12292, 12293, 12315, 12321-12329, 12343-12345, 12347-12349, 12360, 12363, 12366, 12369-12373, 12377, 12380, 12383-12384, 12386-12389, 12392-12394, 12396-12400, 12402-12404, 12406, 12410-12417, 12419-12425, 12427-12439, 12441-12443, 14530-14533, 14537-14538, 14542-14557, 14560-14565, 14568-14582, 14584-14656, 14658-14666, 14668-14670, 14672-14676, 14678-14680, 14682-14690, 14692-14699, 14701-14999, 15002-15149) (at least ten individuals; up to 4 m) basioccipital, splenial, fifteen anterior and mid cervical vertebrae, two mid dorsal vertebrae, posterior dorsal vertebra, eight dorsal vertebrae, few dorsal ribs, gastralium, sacral vertebrae, fifty-eight caudal vertebrae, four chevrons, ischium, three proximal fibulae, astragali, three distal tarsals, seven pedal phalanges, few pedal unguals
(UMNH VP 12279) incomplete scapula (234 mm)
....(UMNH VP 12281) partial coracoid
(UMNH VP 12280) scapula (290 mm)
(UMNH VP 12282) coracoid
(UMNH VP 12284) humerus (255 mm)
....(UMNH VP 12287) ulna (197 mm)
....(UMNH VP 12289) radius (184 mm)
(UMNH VP 12291) semilunate carpal
(UMNH VP 12292) distal carpal I
(UMNH VP 12293) distal carpal II
(UMNH VP 12294) scapholunare
(UMNH VP 12295) intermedium?
(UMNH VP 12296) metacarpal I (42 mm)
(UMNH VP 12297) metacarpal I (43 mm)
....(UMNH VP 12299) metacarpal II (96 mm)
....(UMNH VP 12301) metacarpal III (76 mm)
....(UMNH VP 12303) manual phalanx I-1 (89 mm)
....(UMNH VP 12305) manual phalanx II-1 (69 mm)
....(UMNH VP 12307) manual phalanx II-2 (87 mm)
....(UMNH VP 12309) manual phalanx III-1 (31 mm)
....(UMNH VP 12311) manual phalanx III-2 (28 mm)
....(UMNH VP 12313) manual phalanx III-3 (47 mm)
....(UMNH VP 12314) manual ungual I
....(UMNH VP 12316) manual ungual II
....(UMNH VP 12320) manual ungual III
(UMNH VP 12298) metacarpal II (91 mm)
(UMNH VP 12300) metacarpal III (75 mm)
(UMNH VP 12302) manual phalanx I-1 (81 mm)
(UMNH VP 12304) manual phalanx II-1 (69 mm)
(UMNH VP 12306) manual phalanx II-2 (85 mm)
(UMNH VP 12308) manual phalanx III-1 (38 mm)
(UMNH VP 12310) manual phalanx III-2 (30 mm)
(UMNH VP 12312) manual phalanx III-3 (48 mm)
(UMNH VP 12317) manual ungual II
(UMNH VP 12318) manual ungual II
(UMNH VP 12319) (juvenile) manual ungual I (82 mm)
(UMNH VP 12330) pedal ungual II
(UMNH VP 12331) pedal phalanx
(UMNH VP 12332) pedal phalanx
(UMNH VP 12333) pedal phalanx
(UMNH VP 12334) pedal phalanx
(UMNH VP 12335) pedal phalanx
(UMNH VP 12336) pedal phalanx
(UMNH VP 12337) pedal phalanx
(UMNH VP 12338) pedal phalanx
(UMNH VP 12339) pedal phalanx
(UMNH VP 12340) pedal phalanx
(UMNH VP 12341) pedal phalanx
(UMNH VP 12342) pedal phalanx
(UMNH VP 12346) pedal phalanx
(UMNH VP 12350) pedal phalanx
(UMNH VP 12351) pedal phalanx
(UMNH VP 12352) pedal phalanx
(UMNH VP 12353) pedal phalanx
(UMNH VP 12354) metatarsal II
....(UMNH VP 12355) metatarsal III
....(UMNH VP 12356) metatarsal IV
(UMNH VP 12357) metatarsal IV
....(UMNH VP 12358) metatarsal III
....(UMNH VP 12359) metatarsal II
(UMNH VP 12361) femur
(UMNH VP 12362) tibia
(UMNH VP 12364) astragalus
....(UMNH VP 12365) calcaneum
(UMNH VP 12367) (subadult) proximal fibula
(UMNH VP 12368) partial ilium
(UMNH VP 12374) ischium
(UMNH VP 12375) ischium
(UMNH VP 12376) pedal phalanx I-1
(UMNH VP 12378) three fused sacral centra
(UMNH VP 12379) mid caudal vertebra
(UMNH VP 12381) proximal caudal vertebra
(UMNH VP 12382) first sacral vertebra
(UMNH VP 12385) mid caudal vertebra
(UMNH VP 12390) proximal chevron
(UMNH VP 12391) proximal chevron
(UMNH VP 12395) proximal chevron
(UMNH VP 12401) mid chevron
(UMNH VP 12405) distal caudal vertebra
(UMNH VP 12407) distal caudal vertebra
(UMNH VP 12408) distal caudal vertebra
(UMNH VP 12409) distal caudal vertebra
(UMNH VP 12418) distal caudal vertebra
(UMNH VP 12426) distal caudal vertebra
(UMNH VP 12440) posterior dorsal vertebra
(UMNH VP 14524) frontal
....(UMNH VP 14525) frontal
(UMNH VP 14526) partial maxilla, teeth
(UMNH VP 14527) partial dentary, teeth
(UMNH VP 14528) incomplete dentary, teeth
(UMNH VP 14529) incomplete dentary, teeth
(UMNH VP 14534) mid dorsal vertebra
(UMNH VP 14535) mid dorsal vertebra
(UMNH VP 14536) first dorsal vertebra
(UMNH VP 14539) pubis
(UMNH VP 14540) pubis
(UMNH VP 14541) incomplete ischium
(UMNH VP 14558) quadrate
(UMNH VP 14559) quadrate
(UMNH VP 14566) frontal
(UMNH VP 14567) postorbital
(UMNH VP 14583) pedal phalanx
(UMNH VP 14657) incomplete posterior cervical vertebra
(UMNH VP 14667) (adult) femur
(UMNH VP 14671) furcula
(UMNH VP 14677) (juvenile) atlantal intercentrum
(UMNH VP 14681) posterior surangular fragment
(UMNH VP 14691) second dorsal vertebra
(UMNH VP 14700) mid cervical vertebra
(UMNH VP 15000) incomplete braincase
Referred- (UMNH VP 12447) distal tarsal III (Zanno, 2010b)
(UMNH VP 12451) distal tarsal IV (Zanno, 2010b)
(UMNH VP 12476) distal chevron (Zanno, 2010b)
(UMNH VP 16020) posterior surangular fragment (Zanno, 2010b)
(UMNH VP 16021) partial anterior tooth (Zanno, 2010b)
(UMNH VP 16022) nasal (Zanno, 2010b)
(UMNH VP 16023) partial anterior tooth (Zanno, 2010b)
(UMNH VP 16024) (juvenile) partial fibula (Zanno, 2010b)
Diagnosis- (after Kirkland et al., 2005) hypertrophied basisphenoidal recess; extensive, deeply depressed subcondylar and subotic recesses, each with multiple pneumatic fossae; flexor tubercle of manual ungual I with deep collateral ligament pits.
(after Zanno, 2010b) antorbital fossa extends onto lateral surface of nasal; at least five pairs of conical anterior dentary teeth (also in Erlikosaurus); anteriormost teeth lingually cupped (inapplicable in other therizinosaurs); median ridge on ventral sulcus of cervical vertebrae; infraprezygapophyseal fossa on mid dorsal vertebrae divided into three accessory fossae; accessory caudal centrodiapophyseal lamina on mid dorsal vertebra; hypertrophied, obliquely oriented humeral enteipcondyle with concave posterior margin; pubic tubercle well developed and posterolaterally oriented, placed on anterior edge of acetabulum.
Other diagnoses- Of Kirkland et al.'s (2005) original diagnostic characters, several are now invalid. A ventrally directed basisphenoid recess is plesiomorphic for theropods. The reported enlarged first dentary alveolus is either a preservational or preparation artifact, as there is a small replacement crown preserved in part of it (Zanno, 2006). Zanno states the posterior tuberosity on the distal end of the humerus opposite the radial condyle is more widely distributed among coelurosaurs. In addition, she finds the laterally deflected and biconcave apex of the deltopectoral crest is diagnostic of a more inclusive clade of therizinosaurs, based on unpublished data. The depth of manual ungual I's flexor tubercle is not diagnostic, though the ligament pits are. The lack of a lateral dentary shelf and the elongate distal caudal vertebrae are plesiomorphic for coelurosaurs, while the short distal caudal prezygapophyses are present in all therizinosaurs.
Of Zanno's (2010b) diagnostic characters, an inflated basisphenoid is present in Erlikosaurus and Nothronychus. The postorbital facet on the frontal which extends anterior to the postorbital process is primitive, being seen in Incisivosaurus as well. Anterior teeth which lack serrations are primitive for maniraptoriforms. The groove extending proximally from the entepicondyle of the humerus may be plesiomorphic, as it is also present in Tanycolagreus, Coelurus and Khaan. Zanno also lists "midseries chevrons possessing markedly distinct cranial tubercles", but this is plesiomorphic, being also seen in Caudipteryx and Nomingia.
Comments- The above material comes from at least ten individuals, which were excavated starting in 2001. Some of the pedal phalanges listed under UMNH VP 12331-12353 are pedal unguals. Several mistakes are present regarding the numbering of elements by Zanno (2010)- UMNH VP 14526 is listed as UMNH VP 14565 in her text; 14525 is mistyped 12525 in figure 2; 14539 mislabeled 14529 in figure 13; 12359 is mislabeled 12357 in figure 20A. In addition, UMNH VP 12401 is mislabeled as 12391 in Kirkland et al. (2005).
References- Kirkland, Zanno, DeBlieux, Smith and Sampson, 2004. A new, basal-most therizinosauroid (Theropoda: Maniraptora) from Utah demonstrates a Pan-Laurasian distribution for Early Cretaceous therizinosauroids. Journal of Vertebrate Paleontology. 24(3), 25A.
Smith, Kirkland, Sanders, Zanno and DeBlieux, 2004. A comparison of North American therizinosaur (Theropoda: Dinosauria) braincases. Journal of Vertebrate Paleontology. 24(3), 180A.
Zanno, 2004. The pectoral girdle and forelimb of a primitive therizinosauroid (Theropoda: Maniraptora): New information on the phylogenetics and evolution of therizinosaurs. Journal of Vertebrate Paleontology. 24(3), 8A.
Kirkland, Zanno, Sampson, Clark and DeBlieux, 2005. A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah. Nature. 435, 84-87.
Zanno, 2006. The pectoral girdle and forelimb of a basal therizinosauroid (Theropoda, Maniraptora) with phylogenetic and fuctional implications. Masters thesis, [institution]. [pp].
Zanno, 2006. The pectoral girle and forelimb of the primitive therizinosauroid Falcarius utahensis (Theropoda, Maniraptora): Analyzing evolutionary trends within Therizinosauroidea. Journal of Vertebrate Paleontology. 26(3), 636-650.
Zanno and Erickson, 2006. Ontogeny and life history of Falcarius utahensis, a primitive therizinosauroid from the Early Cretaceous of Utah. Journal of Vertebrate Paleontology. 26(3), 143A.
Zanno and Erickson, 2006. Ontogeny and life history of Falcarius utahensis, a primitive therizinosauroid from the Early Cretaceous of Utah. in Yang, Wang and Weldon (eds). Acient life and modern approaches: Abstracts of the second International Paleontological Congress. University of Science and Technology of China Press, Hefei. 453-454.
Zanno, 2008. A taxonomic and phylogenetic reevaluation of Therizinosauria (Dinosauria: Theropoda): Implications for the evolution of Maniraptora. PhD Thesis. The University of Utah. 329 pp.
Zanno, 2010a. Osteology of Falcarius utahensis: Characterizing the anatomy of basal therizinosaurs. Zoological Journal of the Linnaean Society. 158, 196-230.
Zanno, 2010b. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Smith, Zanno, Sanders, Deblieux and Kirkland, 2011. New information on the braincase of the North American therizinosaurian (Theropoda, Maniraptora) Falcarius utahensis. Journal of Vertebrate Paleontology. 31(2), 387-404.
Lautenschlager, Rayfield, Perle, Zanno and Witmer, 2012. The endocranial anatomy of Therizinosauria and its implications for sensory and cognitive function. PLoS ONE. 7(12), e52289.
Button and Zanno, 2013. Tooth enamel microstructure of the Early Cretaceous therizinosaurian Falcarius utahensis (Theropoda, Maniraptora). Journal of Vertebrate Paleontology. Program and Abstracts 2013, 98.
Herzog, Zanno and Kirkland, 2014. Histological analysis of an enigmatic microstructural paleopathology on limb bones of the theropod dinosaur Falcarius utahensis. Journal of Vertebrate Paleontology. Program and Abstracts 2014, 146-147.
Smith, 2015. Craniocervical myology and functional morphology of the small-headed therizinosaurian theropods Falcarius utahensis and Nothronychus mckinleyi. PLoS ONE. 10(2), e0117281.

unnamed possible therizinosaur (Werner, 1994)
Cenomanian, Late Cretaceous
Wadi Milk Formation, Sudan
Material- (Vb-722) tooth (3.6x2.5x? mm)
References- Werner, 1994. Die kontinentale Wirbeltierfauna aus der unteren Oberkreide des Sudan (Wadi Milk Formation). Berliner Geowissenschaftliche Abhandlungen Reihe E. 13, 221-249.
Rauhut, 1999. A dinosaur fauna from the Late Cretaceous (Cenomanian) of Northern Sudan. Palaeontologia Africana. 35, 61-84.

undescribed therizinosaur (Saegusa, Ikeda and Handa, 2012)
Early Albian, Early Cretaceous
Kamitaki Quarry, Ohyamashimo Formation, Sasayama Group, Hyogo, Japan
Material- (MNHAH coll.) tooth
Comments- Saegusa et al. (2012) reported "From 2010 to 2011, an archaeological excavation of Tambatitanis in Sannan-cho, Tamba City revealed one missing tooth each of Ankylosauria and Therizinosauria. Although it is difficult to identify the detailed taxa of the fallen teeth, the Therizinosauria teeth from the Sasayama group may not be primitive Therizinosauria like Falcarius because of the coarse denticles." (translated)
Reference- Saegusa, Ikeda and Handa, 2012. Additional dinosaur materials from the Sasayama Group of Hyogo Prefecture, SW Japan. Abstracts with Programs the 2012 Annual Meeting of the Palaeontological Society of Japan. 14.

Jianchangosaurus Pu, Kobayashi, Lu, Xu, Wu, Chang, Zhang and Jia, 2013
J. yixianensis Pu, Kobayashi, Lu, Xu, Wu, Chang, Zhang and Jia, 2013
Barremian-Aptian, Early Cretaceous
Yixian Formation, Liaoning, China
Holotype- (~1.9 m; juvenile) incomplete skull, mandibles, hyoid, atlas, axis (25.2 mm), third cervical vertebra (42.5 mm), fourth cervical vertebra (33.2 mm), fifth cervical vertebra (42.6 mm), sixth cervical vertebra (47.4 mm), seventh cervical vertebra (45.5 mm), eighth cervical vertebra (45.9 mm), ninth cervical vertebra (45.5 mm), tenth cervical vertebra (47.2 mm), cervical ribs, first dorsal vertebra, second dorsal vertebra (23 mm), third dorsal vertebra, fourth dorsal vertebra, fifth dorsal vertebra (25.4 mm), sixth dorsal vertebra, seventh dorsal vertebra, eight dorsal vertebra (27.4 mm), ninth dorsal vertebra (27.3 mm), tenth dorsal vertebra, eleventh dorsal vertebra, twelfth dorsal vertebra (26.9 mm), dorsal ribs, sixteen gastralia, first sacral vertebra (29.9 mm), second sacral vertebra, third sacral vertebra, fourth sacral vertebra (30.9 mm), fifth sacral vertebra (28.6 mm), first caudal vertebra (26.6 mm), second caudal vertebra (18.2 mm), third caudal vertebra (23.2 mm), fourth caudal vertebra (24.2 mm), fifth caudal vertebra (25.5 mm), sixth caudal vertebra, seventrh caudal vertebra, eighth caudal vertebra, ninth caudal vertebra, tenth caudal vertebra, eleventh caudal vertebra, four chevrons, scapulae (170.8 mm), coracoids, partial furcula, humeri (158.5 mm), radii (112 mm), ulnae (124.3 mm), scapholunares, partial semilunate carpal, carpal, metacarpals I (28.3 mm), phalanges I-1 (46.6 mm), manual unguals I (54.7 mm), metacarpal II (61 mm), phalanx II-1, phalanx II-2 (40.7 mm), manual ungual II (45.4 mm), metacarpal III (43.9 mm), phalanx III-3 (29.7 mm), incomplete ilum (202.9 mm), pubis (177.8 mm), ischium (148.2 mm), femora (206.6 mm), tibiae (316 mm), fibula (167.1 mm), partial metatarsals (mtIII ~171 mm), five pedal phalanges, four pedal unguals, feathers
Diagnosis- (after Pu et al., 2013) 27 tightly packed maxillary teeth; dorsal border of the antorbital fenestra formed by maxilla, nasal, and lacrimal, with the majority of the border formed by the nasal; no participation of jugal in margin of antorbital fenestra; a short diastema in anterior tip of dentary; concave labial surface and convex lingual surface of dentary teeth (except six anterior teeth); lack of prominent hypapophyses in anterior dorsal vertebrae; proximal caudal centra with an oval cross section and articular facet as tall as wide; weakly curved manual unguals with weak flexor tubercles ventral to articular facet; shallow and elongated ilium; a ridge bounding cuppedicus fossa confluent with acetabular rim; extensive contact between pubic apron.
Comments- The holotype was bought by the Henan Geological Museum from a private dealer, so lacks an exact stratigraphic position and has been partially rearranged with mostly sculpted metatarsals. In addition, the authors misidentified some elements. The supposed right surangular and angular seem to just be the left surangular, while the supposed left jugal is the left prearticular. The supposed left articular is too large, and seems better identified with the supposed left angular as the right surangular. In the postcranium, the supposed right metacarpal II is shorter and differently shaped compared to the left. It would make more sense as a phalanx II-1.
Pu et al. (2013) recovered Jianchangosaurus intermediate between Falcarius and Beipiaosaurus using Zanno's TWiG matrix, a placement confirmed by Hartman et al. (2019). Cau (2018) oddly found it as the basalmost alvarezsauroid, but that takes 18 more steps in Hartman et al.'s amtrix so is extremely unlikely.
References- Lu, Kobayashi, Xu, Pu and Wu, 2010. A new basal therizinosauroid from the Lower Cretaceous Yixian Formation of Liaoning, China. Journal of Vertebrate Paleontology. Program and Abstracts 2010, 124A.
Kobayashi, Lu, Pu, Xu and Wu, 2012. Ornithischian-like dental arrangement in a basal therizinosaur dinosaur from Northeastern China. Journal of Vertebrate Paleontology. Program and Abstracts 2012, 122.
Pu, Kobayashi, Lu, Xu, Wu, Chang, Zhang and Jia, 2013. An unusual basal therizinosaur dinosaur with an ornithischian dental arrangement from Northeastern China. PLoS ONE. 8(5), e63423.
Cau, 2018. The assembly of the avian body plan: A 160-million-year long process. Bollettino della Società Paleontologica Italiana. 57(1), 1-25.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247.

Therizinosauroidea Maleev, 1954 vide Russell and Dong, 1994
Definition- (Beipiaosaurus inexpectus + Therizinosaurus cheloniformis) (Zanno, 2010; modified from Clark, Maryanska and Barsbold, 2004)
Other definitions- (Therizinosaurus cheloniformis <- Ornithomimus velox, Oviraptor philoceratops, Velociraptor mongoliensis, Passer domesticus) (modified from Zhang, Xu, Sereno, Kwang and Tan, 2001)
(Therizinosaurus cheloniformis <- Oviraptor philoceratops, Passer domesticus) (modified from Hu, Hou, Zhang and Xu, 2009)
References- Maleev, 1954. New turtle-like reptile in Mongolia. Priroda. 1954, 106-108.
Russell and Dong, 1994. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences. 30(10), 2107-2127.
Zhang, Xu, Sereno, Kwang and Tan, 2001. A long-necked therizinosauroid dinosaur from the Upper Cretaceous Iren Dabasu Formation of Nei Mongol, People’s Republic of China. Vertebrata PalAsiatica. 39(4), 282-290.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. in In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Hu, Hou, Zhang and Xu, 2009. A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus. Nature. 461, 640-643.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

undescribed Therizinosauroidea (Dong, 1992)
Middle-Late Campanian, Late Cretaceous
Iren Dabasu Formation, Inner Mongolia, China
Material- (Erenhot Dinosaur Museum coll.) dentary, teeth (Currie and Eberth, 1993)
(IVPP coll.) (isolated) many limb elements (Dong, 1992)
(IVPP and PIN coll.) tens of specimens (Cuirrie and Eberth, 1993)
Comments- Currie and Eberth (1993) stated "A rough tally of Sino-Soviet field identifications shows that ... 'theropods' (including large theropods, small theropods and segnosaurs, but not ornithomimids) were more common (400 specimens)" and that "The apparent high numbers of carnivorous dinosaurs can be attributed mostly to ornithomimids [>1000 elements] and segnosaurids" indicating some significant number of those 400 'theropods' found in June-July 1959 were therizinosaurs.
Dong (1992) reported "In July 1988, the expedition of the CCDP came to Erenhot (Fig.85) where they collected ... Many limb bones [which] might be identified as segnosaurs" and listed Segnosaurus sp. as being present in the formation. He later (1993) said "at least two taxa of segnosaurs" were represented. Currie and Eberth (1993) stated "isolated elements were commonly recovered by the Sino-Canadian expeditions in 1988 and 1990. A well-preserved dentary with teeth is in the collections of the Erenhot Dinosaur Museum. The isolated elements are indistinguishable from Erlicosaurus andrewsi and Segnosaurus ghalbiensis bones in the collections of the Paleontological Institute (at the Central State Museum) in Ulaan Baatar. There are a few elements from the Iren Dabasu that may also be referable to the more poorly known segnosaur Enigmosaurus." They listed both Segnosaurus sp. and Erlikosaurus sp. as present, but given the poor state of knowledge of therizinosaur diversity in the early 90s, they may actually belong to the contemporaneous Erliansaurus, Neimongosaurus, and/or the taxon to which the forelimb AMNH 6368 belongs instead. Precise localities have not been published, but the CCDP excavated several (Currie and Eberth, 1993: Table 3), all around Iren Nor and far from Sanhangobi where Erliansaurus and Neimongosaurus were found.
References- Dong, 1992. Dinosaurian Faunas of China: China Ocean Press. 188 pp.
Currie and Eberth, 1993. Palaeontology, sedimentology and palaeoecology of the Iren Dabasu Formation (Upper Cretaceous), Inner Mongolia, People’s Republic of China. Cretaceous Research. 14, 127-144.
Dong, 1993. The field activities of the Sino-Canadian Dinosaur Project in China, 1987-1990. Canadian Journal of Earth Sciences. 30(10), 1997-2001.

undescribed Therizinosauroidea (Watabe and Weishampel, 1994)
Cenomanian-Santonian, Late Cretaceous
Bayshin Tsav, Baynshiren Formation, Mongolia
(IGM coll.; 010725 AMT-N) scapula (Watabe, Tsogtbaatar, Ichinnorov and Barsbold, 2004)
Cenomanian-Santonian, Late Cretaceous
Bayshin Tsav, Baynshiren Formation, Mongolia
(HMNS 94-3-11; 930820 BTs-II-4) humerus (Watabe and Suzuki, 2000a)
(HMNS 94-3-15; 930820 BTs-II-8) pubis (Watabe and Suzuki, 2000a)
(IGM coll.; 940625 BTs II) partial skull, mandible, cervical vertebrae (Watabe and Suzuki, 2000b)
(not collected?) sacrum, anterior ilia, pubes (Watabe and Suzuki, 2000a)
Cenomanian-Santonian, Late Cretaceous
Khara Khutul, Baynshiren Formation, Mongolia
(IGM 100/84) femoral (or tibial?) shaft (~1050 mm) (Zanno, 2010)
Cenomanian-Santonian, Late Cretaceous
Urlibe Khudak, Baynshiren Formation, Mongolia
(IGM coll.) ulna, radius, carpals, manus including manual ungual I, metacarpal II, incomplete metacarpal III and claw sheath (Kobayashi, Tsogtbaatar, Tsogtbaatar and Barsbold, 2015)
Cenomanian-Santonian, Late Cretaceous
Shine Us Khuduk, Baynshiren Formation, Mongolia
(IGM coll.) material ( Barsbold, Kobayashi and Kubota, 2007)
Comments- Watabe and Wishampel (1994) originally noted in an abstract "several well-preserved segnosaur specimens ... were collected from Baishin Tsav", but more details were given in the 2000 papers about the expeditions. Watabe and Suzuki (2000a) listed field number 930820 BTs-II-4 as "Segnosaurid left humerus" and field number 930820 BTs-II-8 (in part) as "segnosaur pubis", both found in August 20 1993. They photograph "pelvic part of segnosaurian from Bayshin Tsav (eastern Gobi region)", showing an articulated sacrum, anterior ilia and partial pubes, but do not provide a field number. This is presumably the "well preserved pelvis (M. Watabe pers. comm., December 2006)" cited by Zanno (2010). The humerus and pubis were prepared the next year and given the specimen numbers HMNS 95-3-15 and 94-3-11 respectively (Matsumoto et al., 2000). Watabe and Suzuki (2000b) state "cranial and postcranial elements of Segnosauria were found" in June 1994, and "A skeleton of Segnosauria was collected from BTs-II, which had been discovered in 1993." They listed 940625 BTs II as "Segnosaurid lower jaw, part of skull, cervical v.". Watabe and Suzuki (2000c) summed up the finds as "partial bones of the skull, cervical vertebrae and pubis of a segnosauria." Erlikosaurus and cf. Segnosaurus are known from that locality, and Enigmosaurus is also known from the formation. 930820 BTs-II-4 could be compared to all three, 930820 BTs-II-8 could be compared to Enigmosaurus and Segnosaurus (though the photo can't be distinguished from either), and 940625 BTs II could be compared to Erlikosaurus and Segnosaurus.
Watabe et al. (2004) report a "large-sized scapula" discovered on July 22 2001 at Amtgai, and excavated on July 25. They stated "The coracoid was missing in the scapula, however, the relative size of the coracoid to the scapula is estimated as disproportionally large." "The morphology of the scapula is close to that of therizinosaurid." It was photographed as plate 5 figure 1, and prepared in 2003 (Tsogtbaatar and Chinzorig, 2010).
Barsbold et al. (2007) report disarticulated therizinosauroid material from Shine Us Khuduk found in 2005-2006.
Zanno (2010) stated "A large left femur (estimated length 105 cm) is labelled IGM 100/84 [the holotype specimen number of Enigmosaurus], yet is clearly not associated with the pelvis due to its massive size, which more closely approximates that of Segnosaurus." Segnosaurus is also known from that locality, so this may be its actual identity.
Kobayashi et al. (2015) reported a therizinosaur from Urlibe Khudak found in 2012 which has a strongly reduced metacarpal III and no preserved digit III phalanges. This could be compared to both Segnosaurus and Enigmosaurus, but notably no other Baynshiren specimens are complete enough to evaluate manual digit III form.
References- Watabe and Weishampel, 1994. Results of Hayashibara Museum of Natural Sciences–Institute of Geology, Academy of Sciences of Mongolia Joint Paleontological Expedition to the Gobi desert in 1993. Journal of Vertebrate Paleontology. 14(3), 51A.
Matsumoto, Hashimoto and Sonoda, 2000. Report of preparation works for Mongolian specimens in HMNS from March 1994 to December 1998. Hayashibara Museum of Natural Sciences Research Bulletin. 1, 113-127.
Watabe and Suzuki, 2000a. Report on the Japan - Mongolia Joint Paleontological Expedition to the Gobi desert, 1993. Hayashibara Museum of Natural Sciences Research Bulletin. 1, 17-29.
Watabe and Suzuki, 2000b. Report on the Japan - Mongolia Joint Paleontological Expedition to the Gobi desert, 1994. Hayashibara Museum of Natural Sciences Research Bulletin. 1, 30-44.
Watabe and Suzuki, 2000c. Cretaceous Fossil Localities and a List of Fossils Collected by the Hayashibara Museum of Natural Sciences and Mongolian Paleontological Center Joint Paleontological Expedition (JMJPE) from 1993 through 1998. Hayashibara Museum of Natural Sciences Research Bulletin. 1, 99-108.
Watabe, Tsogtbaatar, Ichinnorov and Barsbold, 2004. Report on the Japan - Mongolia Joint Paleontological Expedition to the Gobi desert, 2001. Hayashibara Museum of Natural Sciences Research Bulletin. 2, 69-96.
Barsbold, Kobayashi and Kubota, 2007. New discovery of dinosaur fossils from the Upper Cretaceous Bayanshiree Formation of Mongolia. Journal of Vertebrate Paleontology. 27(3), 44A.
Tsogtbaatar and Chinzorig, 2010. Fossil specimens prepared in Mongolian Paleontological Center: 2002–2008. Hayashibara Museum of Natural Sciences Research Bulletin. 3, 155-166.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Kobayashi, Tsogtbaatar, Tsogtbaatar and Barsbold, 2015. A new therizinosaur with functionally didactyl hands from the Bayanshiree Formation (Cenomanian-Turonian), Omnogovi Province, southeastern Mongolia. Journal of Vertebrate Paleontology. Program and Abstracts 2015, 157.

Beipiaosaurus Xu, Tang and Wang, 1999
B. inexpectus Xu, Tang and Wang, 1999
Late Barremian-Early Aptian, Early Cretaceous
Jianshangou member of Yixian Formation, Liaoning, China
Holotype- (IVPP 11559) (~1.85 m; 45 kg; subadult) (skull ~265 mm) nasal?, postorbital, parietal, prootic, skull fragments, dentary (~172 mm), teeth, three cervical vertebrae (~32 mm), four fused posterior dorsal vertebrae (each ~44 mm), four proximal dorsal ribs, fourth sacral vertebra, fifth sacral vertebra, first caudal vertebra, second caudal vertebra, third caudal vertebra, fourth caudal vertebra, fifth caudal vertebra, sixth caudal vertebra, seventh caudal vertebra, eighth caudal vertebra, ninth caudal vertebra, tenth caudal vertebra, eleventh caudal vertebra, twelfth caudal vertebra, two mid caudal vertebrae, mid caudal centrum (lost), eight distal caudal vertebrae, two fused distal caudal vertebrae, pygostyle, fourth chevron, sixth chevron, tenth chevron, incomplete scapula, coracoids, partial furcula, partial humeri (distal humerus lost), proximal radii (one lost), distal radii, proximal ulna (lost), distal ulnae, scapholunare, proximal carpal, distal carpal I, distal carpals II, metacarpals I, partial phalanges I-1, manual ungual I, metacarpals II (70 mm), phalanges II-1, phalanges II-2, manual unguals II, metacarpal III, phalanges III-1, phalanges III-2, phalanges III-3, manual unguals III (one proximal), ilia (193 mm), incomplete pubis, incomplete ischia, ischial fragment (lost), femur (265 mm), femoral fragment, tibiae (one incomplete) (275 mm), incomplete fibula, astragalus, calcaneum, distal tarsal, metatarsal I, pedal ungual I, metatarsal II (97 mm), metatarsal III (107 mm), metatarsal IV, metatarsal V, three pedal phalanges, pedal ungual (lost), feathers
Referred- (STM31-1) skull, sclerotic ring, mandible, atlas, axis, third cervical vertebra, fourth cervical vertebra, fifth cervical vertebra, sixth cervical vertebra, seventh cervical vertebra, eighth cervical vertebra, ninth cervical vertebra, tenth cervical vertebra, eleventh cervical vertebra, seventeen cervical ribs, dorsal vertebrae, twelve dorsal ribs, scapulae, coracoids, humeri (one proximal), radii (one distal), ulnae (one distal), carpals, metacarpal I, proximal metacarpal II, proximal metacarpal III, feathers (Xu, Zheng and You, 2009)
(~2 m) vertebrae, fragmentary limb elements including humerus and tibia, skin impressions, feathers (Yao, Zhang and Tang, 2002)
Diagnosis- (after Xu et al., 1999) large skull, about equal to femoral length; proximodistally elongate lateral articular surface on the flexor side of manual phalanx I-1.
(after Zanno, 2010) four fused posterior dorsal vertebrae; pygostyle; lateral buttress of metacarpal I triangular; obturator process of ischium sinusoidal with ventrally deflected distal portion; ischial boot twice width of distal shaft; mediodistal ridge on anterior femur.
(proposed) lateral buttress of metacarpal I developed about 40% down shaft.
Other diagnoses- Several characters listed by Xu et al. (1999) in their diagnosis are plesiomorphic for therizinosaurs- short and bulbous tooth crowns; large tibiofemoral ratio (104%); first metatarsal does not contact tarsus; proximally compressed metatarsus. The elongate manus (>110% of femoral length) may be plesiomorphic too, as it is shared with Protarchaeopteryx and avialans, and approached by microraptorians and Jinfengopteryx. The large skull (about equal to femoral length) may not be plesiomorphic though (contra Zanno), as outgroups (oviraptorosaurs, most basal troodontids, scansoriopterygids, alvarezsauroids, Ornitholestes) have smaller skulls. The discovery of a complete ilium by Xu et al. (2003) shows the preacetabular process is not shallow.
Clark et al. (2004) listed the subequal pre- and postacetabular processes and uncompressed ischial shaft in their diagnosis, but these are primitive for therizinosaurs.
Comments- The holotype was discovered in 1996, with the quarry reexcavated by 2002 and further material discovered (Xu et al., 2003).
The cervicals were about 32 mm, while the posterior dorsals were 44 mm. The cervical series is estimated to be 304 mm, and the dorsal series was about 430 mm. This is based on comparison to Neimongosaurus, compensating for a vertebral count of twelve cervicals and ten dorsals. The preserved caudal is most similar to the fourth of Neimongosaurus in central proportions and was about 32 mm, suggesting a tail length of 635 mm. The sacrum may have been about 220 mm, assuming it had five vertebrae. The skull length is difficult to determine precisely because how much of the dentary is preserved is neither described, nor discernable from the photos. The preserved length is said to be 65% of femoral length, which results in 172 mm. In Erlikosaurus, the dentary is 68% of mandibular length, so Beipiaosaurus' mandible was at least 253 mm long. Again, using Erlikosaurus for a craniomandibular ratio results in a skull at least 265 mm long. The total length of Beipiaosaurus was therefore about 1.85 meters long.
References- Xu, Tang and Wang 1999. A therizinosauroid dinosaur with integumentary structures in China. Nature. 399, 350-354.
Yao, Zhang and Tang, 2002. Small spheres preserved in a therizinosauroid dinosaur's blood vessels from northeast China. Acta Scientiarum Naturalium Universitatis Pekinensis. 38(2), 221-225.
Xu, Cheng, Wang and Chang, 2003. Pygostyle-like structure from Beipiaosaurus (Theropoda, Therizinosauroidea) from the Lower Cretaceous Yixian Formation of Liaoning, China. Acta Geologica Sinica. 77(3), 294-298.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. in In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Xu, Zheng and You, 2009. A new feather type in a nonavian theropod and the early evolution of feathers. Proceedings of the National Academy of Sciences. 106(3), 832-834.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

unnamed possible therizinosaur (Averianov, 2007)
Santonian, Late Cretaceous
Bostobe Formation, Kazakhstan
Material- (N 601/12457) (~3.26 m; adult) femur (512 mm)
Comments- Nessov (1995) referred the femur N 601/12457 to Tarbosaurus sp., but Carr (2005) determined it lacks the synapomorphies of Tarbosaurus + Tyrannosaurus and of Alectrosaurus. Averianov (2007) later excluded the femur from Tyrannosauridae (cylindrical anterior trochanter, extensor groove absent) and noted particular characters similar to therizinosauroids (low and rounded greater trochanter; straight lateral margin with little or no lateral expansion of the lateral condyle; low crescentic fourth trochanter). In particular, Averianov found it to be virtually identical to Neimongosaurus, except for being larger and more robust, referring to it as cf. Neimongosaurus sp.. However, Zanno (2010) noted the femur lacks three characters found in Neimongosaurus and other derived therizinosaurs- elevated head; greater trochanter separated from head by cleft; head with constricted connection to greater trochanter in proximal view. Zanno did not state whether she believed the femur could be from a less derived therizinosaur, though Falcarius does lack these characters, while Beipiaosaurus has the first but not the second. Alxasaurus seems to have the second two characters at least. Yet Falcarius and Beipiaosaurus differ from this femur and Alxasaurus in having wing-like anterior trochanters. Falcarius also lacks the straight lateral margin and cresentric fourth trochanter present in this femur and Beipiaosaurus. Thus if it is a therizinosaur, it seems closest to Beipiaosaurus. Olshevsky (DML, 1996) incorrectly translated 'femur' as 'ilium', leading to the records of a Kazakh Tarbosaurus ilium.
References- Nessov, 1995. Dinosaurs of Northern Eurasia: new data about assemblages, ecology and paleobiogeography. Scientific Research Institute of the Earth's Crust, St. Petersburg State University, St. Petersburg, Russia: 156 pp. + 14 pl. [in Russian with short English, German, and French abstracts].
Olshevsky, DML 1996. https://web.archive.org/web/20201120062312/http://dml.cmnh.org/1996Feb/msg00835.html
Kordikova, Gunnell, Polly and Kovrizhnykh, 1996. Late Cretaceous and Paleocene vertebrate paleontology and stratigraphy in the North-eastern Aral Sea region, Kazakhstan. Journal of Vertebrate Paleontology. 16(3), 46A.
Carr, 2005. Phylogeny of Tyrannosauroidea (Dinosauria: Coelurosauria) with special reference to North American forms. Unpublished PhD dissertation. University of Toronto. 1170 pp.
Averianov, 2007. Theropod dinosaurs from Late Cretaceous deposits in the northeastern Aral Sea region, Kazakhstan. Cretaceous Research. 28(3), 532-544.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

unnamed clade (Alxasaurus elesitaiensis + Therizinosaurus cheloniformis)

undescribed therizinosauroid (Alifanov and Averianov, 2006)
Early Santonian, Late Cretaceous
Yalovach Formation, Tajikistan
Material- (PIN coll.) sacral vertebra, manual phalanges, manual unguals, femur
Comments- The femur is very similar to Erliansaurus, Bissekty therizinosaurs and ZIN PH 24/49 from the Bostobe Formation (Averianov, 2007). Supposed oviraptorids mentioned by Nessov (1995) from this formation are likely based on therizinosaur remains (Alifanov and Averianov, 2006).
Reference- Alifanov and Averianov, 2006. On the finding of ornithomimid dinosaurs (Saurischia, Ornithomimosauria) in the Upper Cretaceous beds of Tajikistan. Paleontological Journal. 40(1), 103-108.
Averianov, 2007. Theropod dinosaurs from Late Cretaceous deposits in the northeastern Aral Sea region, Kazakhstan. Cretaceous Research. 28(3), 532-544.

Therizinosauroidea indet. (Averianov, 2007)
Turonian-Coniacian, Late Cretaceous
Zhirkindek Formation, Kazakhstan
Material- (ZIN PH 1/49) distal metacarpal III
(ZIN PH 32/49) (juvenile) sacral centrum (43.9 mm)
(ZIN PH 38/49) proximal femur
(ZIN PH 39/49) proximal femur
Comments- The femora differ from N 601/12457 from the Bostobe Formation, but are similar to other Bostobe therizinosaur femora, Erliansaurus, Bissekty therizinosaurs and a femur from the Yalovach Formation.
Reference- Averianov, 2007. Theropod dinosaurs from Late Cretaceous deposits in the northeastern Aral Sea region, Kazakhstan. Cretaceous Research. 28(3), 532-544.

Therizinosauroidea indet. (Rozhdestvensky, 1964)
Santonian, Late Cretaceous
Bostobe Formation, Kazakhstan
Material- (IZK 2/1) manual ungual (Suslov, 1982)
(IZK 2/2) pedal(?) ungual (Suslov, 1982)
(IZK 2/3) pedal(?) ungual (Suslov, 1982)
(PIN 2229/19) manual ungual (~200 mm) (Rozhdestvensky, 1964)
(ZIN PH 24/49) proximal femur (Averianov, 2007)
(ZIN PH 25/49) pedal phalanx III/IV-? (42.2 mm) (Averianov, 2007)
(ZIN PH 35/49) tooth (FABL 2.2 mm) (Averianov, 2007)
(ZIN PH 37/49) proximal femur (Averianov, 2007)
(ZIN PH 46/49) frontal (Averianov, 2016)
Comments- Rozhdestvensky (1964) described a manual ungual as a therizinosaurid, and later (Rozhdestvensky and Khozatsky, 1967) referred it to cf. Alectrosaurus based on similarity to the therizinosauroid manual ungual preserved with that tyrannosauroid. Suslov (1982) described three unguals as dromaeosaurid, but these were reidentified as therizinosaurian by Nessov (1995). Averianov (2007) also noted the therizinosauroid identity of these remains and described additional elements from the same formation. The femora differ from N 601/12457 from the same formation, but are similar to Erliansaurus, Zhirkindek and Bissekty therizinosaurs and a femur from the Yalovach Formation. The other material is also indistinguishable from Bissekty therizinosaurs.
References- Rozhdestvensky, 1964. New data on occurrences of dinosaurs in Kazakhstan and Central Asia. Tashkent State University, Scientific Publications: Geology. 234, 227-241.
Rozhdestvensky and Khozatsky, 1967. Late Mesozoic terrestrial vertebrates of Asiatic part of the USSR. in Martinson (ed). Stratigraphy and Paleontology of Mesozoic and Paleogene–Neogene Continental Deposits of Asiatic Part of the USSR. Nauka, Leningrad. 82-92. in Russian]
Rozhdestvensky, 1970. About giant ungual phalanges of enigmatic Mesozoic vertebrates. Paleontologicheskii Zhurnal. 1, 131-141.
Suslov, 1982. Ungual phalanges of a dromaeosaurid from the Upper Cretaceous deposits of the Kzyl-Ordinskaya Region. Matyerialy po istorii fauny i flory Kazakhstana. 8, 5-16.
Nessov, 1995. Dinosaurs of nothern Eurasia: new data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.
Averianov, 2007. Theropod dinosaurs from Late Cretaceous deposits in the northeastern Aral Sea region, Kazakhstan. Cretaceous Research. 28(3), 532-544.
Averianov, 2016 (online 2015). Frontal bones of non-avian theropod dinosaurs from the Upper Cretaceous (Santonian-?Campanian) Bostobe Formation of the northeastern Aral Sea region, Kazakhstan. Canadian Journal of Earth Sciences. 53(2). 168-175.

undescribed Therizinosauroidea (Lee, Barsbold, Jacobs and Currie, 2008)
Early Maastrichtian, Late Cretaceous
Nemegt Formation, Mongolia
Material- (IGM coll.) partial skeleton(s)
Comments- Lee et al. (2008) state in an abstract thay they "collected fossils, including ... therizinosaurids" in 2006 and that "most specimens are partially complete skeletons." Prospected localities were "Ulan Khushu, Altan Uul, Bugin Tsav, and Guriliin Tsav."
Reference- Lee, Barsbold, Jacobs and Currie, 2008. A short report of Korea-Mongolia International Dinosaur Project (1st and 2nd year). Journal of Vertebrate Paleontology. 28(3), 104A-105A.

Alxasauridae Russell and Dong, 1994
Comments- Russell and Dong (1994) erected this as a monotypic family- "We thus propose the family -group taxon Alxasauridae to receive Alxasaurus, which, in the absence of other known taxa, is also defined by the above diagnosis for A. elesitaiensis." No other taxa have been proposed to be closer to Alxasaurus than to Therizinosaurus in published analyses.
Reference- Russell and Dong, 1994. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences. 30(10), 2107-2127.
Alxasaurus Russell and Dong, 1994
A. elesitaiensis Russell and Dong, 1994
Aptian-Albian, Early Cretaceous
Bayan Gobi Formation, Inner Mongolia, China
Holotype- (IVPP V88402a; some lost, see comments) (3.78 m; 380 kg) dentary, teeth (3.7-7.2 mm), cervical vertebra (95 mm), cervical vertebra, cervical vertebra, cervical vertebra (95 mm), cervical vertebra (90 mm), two cervical ribs (95, 95 mm), posterior dorsal vertebra, posterior dorsal vertebra, posterior dorsal vertebra (80 mm), posterior dorsal vertebra (80 mm), posterior dorsal vertebra (80 mm), posterior dorsal vertebra, posterior dorsal vertebra (62 mm), six incomplete dorsal ribs, dorsal rib fragments, (sacrum- 345 mm), first sacral vertebra (61 mm), second sacral vertebra (63 mm), third sacral vertebra (70 mm), fourth sacral vertebra (77 mm), fifth sacral vertebra (70 mm), sacral ribs 1-4, caudal vertebrae 1-19 (first caudal vertebra (60 mm), second caudal vertebra (63 mm), third caudal vertebra (61 mm), fourth caudal vertebra (65 mm), fifth caudal vertebra (65 mm), sixth caudal vertebra (62 mm), seventh caudal vertebra (60 mm), eighth caudal vertebra (60 mm), ninth caudal vertebra (58 mm), tenth caudal vertebra (56 mm), eleventh caudal vertebra (51 mm), twelfth caudal vertebra (52 mm), thirteenth caudal vertebra (49 mm), fourteenth caudal vertebra (42 mm), fifteenth caudal vertebra (44 mm), sixteenth caudal vertebra (44 mm), seventeenth caudal vertebra (42 mm), eighteenth caudal vertebra (39 mm), ninteenth caudal vertebra (35 mm), distal caudal vertebra (29 mm), distal caudal vertebra (26 mm), first chevron (114 mm), second chevron (102 mm), third chevron (91 mm), fourth chevron (85 mm), fifth chevron (78 mm), sixth chevron (75 mm), seventh chevron (73 mm), eighth chevron (65 mm), ninth chevron (61 mm), tenth chevron (61 mm), eleventh chevron (52 mm), twefth chevron (55 mm), fourteenth chevron (45 mm), fifteenth chevron (40 mm), scapulocoracoids (520+98 mm), humeri (375 mm), radii (245 mm), ulnae (268 mm), scapholunare, intermedium, distal carpals I, distal carpal II, distal carpal III, metacarpals I (one fragmentary; 55 mm), partial phalanx I-1, manual ungual I (130 mm), metacarpals II (one fragmentary; 111 mm), partial phalanx II-1, partial phalanx II-2, manual ungual II (113 mm), metacarpals III (one fragmentary; 85 mm), partial phalanx III-1, proximal phalanx III-2, ilia (500 mm), ischial shafts, femora (one proximal; 555 mm)
Paratypes- (IVPP V88402b; some lost, see comments) (~2.49 m; 110 kg) posterior cervical vertebra (70 mm), posterior cervical vertebra (70 mm), posterior cervical vertebra (60 mm), dorsal vertebra, dorsal vertebra (45 mm), dorsal vertebra (48 mm), dorsal vertebra (45 mm)
(IVPP V88501; some lost, see comments) (~2.83 m; 160 kg) dorsal vertebra (48 mm), dorsal vertebra (48 mm), dorsal vertebra (53 mm), dorsal vertebra (54 mm), dorsal vertebra (56 mm), first sacral centrum (55 mm), incomplete second sacral centrum, proximal metacarpal I, partial phalanx I-1, manual ungual I (111 mm straight, 128 mm on curve), proximal phalanx II-1, distal phalanx II-2, manual ungual II (105 mm straight, 121 mm on curve), distal metacarpal III, phalanx III-2 (44 mm), proximal manual ungual III, posterior ilium, proximal femora, distal femur, proximal tibiae, distal tibia, proximal fibulae, distal metatarsal I, distal metatarsal II, phalanx II-1 (69 mm), phalanx II-2 (43 mm), pedal ungual II (65 mm straight, 73 mm on curve), distal metatarsal III, phalanx III-1 (60 mm), phalanx III-2 (35 mm), phalanx III-3 (37 mm), pedal ungual III (63 mm straight, 68 mm on curve), distal metatarsal IV, phalanx IV-1 (58 mm), phalanx IV-2 (32 mm), phalanx IV-4 (28 mm), pedal ungual IV (55 mm straight, 62 mm on curve)
Referred- ?(IVPP V88301) vertebrae, ribs, appendicular material (Russell and Dong, 1994)
?(IVPP V88510) appendicular material (Russell and Dong, 1994)
incomplete skull (Dong, 2003)
Diagnosis- (after Russell and Dong, 1994) about forty dentary teeth (also in Beipiaosaurus); preacetabular process ~170% of length across peduncles.
(after Zanno, 2010) anteroproximal blade of proximal chevrons with pronounced lateral flare at region of bifurcation into articular facet.
Other diagnoses- A few of the characters listed by Russell and Dong (1994) in their diagnosis are plesiomorphic- teeth in symphyseal region of dentary; ligament pits well developed in manual phalanges; preacetabular process of ilium moderately expanded; pedal unguals II-IV shorter or subequal to first phalanx in digit. The absence of fusion between cervical ribs and vertebrae is possibly ontogenetic, as it is present in the more basal Falcarius. Contra Zanno (2010), the elongate preacetabular process is not primitive, as it is only otherwise seen in Epidexipteryx and some birds. Similarly, the large number of dentary teeth is not necessarily plesiomorphic, as Falcarius, oviraptorosaurs, and basal members of paravian lineages have less, though Beipiaosaurus and arctometatarsalians have at least as many.
Comments- Note that while volume 30(10) of the Canadian Journal of Earth Sciences lists its date as October 1993, it was not published until February or March of 1994.
This was discovered in 1988 and first announced in 1989 by Dong et al. who remarked on "four mediumsized theropods, including one nearly complete skeleton. An evaluation of the relationships these carnivores will constitute a very interesting systematic and biogeographic problem", with a photo of IVPP V88402a in situ as Plate I Figure 2. It was listed in Olshevsky (1991) as "To be described from China; a primitive form that according to D. A. Russell (pers. comm.) displays conclusive evidence that segnosaurians are derived theropods and not sauropodomorphs." Dong (1992) later stated "A new segnosaur has been found by the CCDP from Early Cretaceous of the Ordos Basin." Zanno (2010) notes most of the material of IVPP V88402 could not be located when she visited the museum. Material which was present is- five dorsal vertebrae, proximal dorsal ribs, two sacral vertebrae, fourteen caudal vertebrae, ten chevrons, scapholunare, distal carpal I, proximal metacarpal I, manual ungual I, proximal metacarpal II, manual ungual II, and two appendicular fragments. Material of IVPP V88501 which was present includes- three dorsal centra, one and a half sacral centra, proximal metacarpal I, proximal manual ungual I, proximal metacarpal II, distal phalanx II-1, proximal phalanx III-3, proximal manual ungual III, manual phalangeal fragments, distal metatarsals and partial pedal phalanges.
Alxasaurus elesitaiensis is known from five individuals, but only three have published measurements. The holotype (IVPP V88402a) is largest, while IVPP V88501 is about 75% as large, and IVPP V88402b is said to be about 66% as large. The skull was about 370 mm long, judging by the dentary. Using Neimongosaurus, but estimating for a more plesiomorphic vertebral count, generates lengths of 904 mm and 605 mm for the cervical and dorsal series respectively. The cervicals were comparatively shorter in Alxasaurus. Finally, the sacrum was 345 mm long, and the tail was 1554 mm long, accounting for the several missing vertebrae (which also total around 28). This totals to 3.78 meters, remarkably close to Russell and Dong's 3.8 meter estimate based on a probably inaccurate presacral formula (10 cervicals, 13 dorsals). IVPP V88501 would then be about 2.83 meters, and IVPP V88402b about 2.49 meters.
References- Dong, Currie and Russell, 1989. The 1988 field program of the Dinosaur Project. Vertebrata Palasiatica. 27(3), 233-236.
Olshevsky, 1991. A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings. 2, 196 pp.
Dong, 1992. Dinosaurian Faunas of China. China Ocean Press. 188 pp.
Russell and Dong, 1994. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences. 30(10), 2107-2127.
Dong, 2003. Contributions to new dinosaur materials from China to dinosaurology. Memoir of the Fukui Prefectural Dinosaur Museum. 2, 123-132.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

"Chilantaisaurus" zheziangensis Dong, 1979
Cenomanian-Turonian, Late Cretaceous
Tangshang Formation (=Fangyan Formation), Zhejiang, China
Holotype- (ZhM V.001) (~5 m; ~900 kg) proximal tibia, partial metatarsal I, phalanx I-1, pedal ungual I, distal metatarsal II, phalanx II-1, phalanx II-2 (74 mm), pedal ungual II, phalanx III-1, phalanx III-2, phalanx III-3, pedal ungual III, phalanx IV-4, pedal ungual IV, pedal ungual fragment
Other diagnoses- Dong (1979) distinguished this species from C. tashuikouensis based on the slightly more robust ungual and later temporal occurence. Yet he was comparing a pedal ungual to a manual ungual, so the diagnosis and taxonomic referral are invalid.
Comments- This specimen was discovered in 1972 and initially described as a megalosaurid referrable to Chilantaisaurus based on perceived similarities between its pedal ungual I and C. tashuikouensis' manual ungual I. Barsbold and Maryanska (1990) considered this a possible segnosaur based on its short pedal phalanges and enlarged, strongly curved unguals. Hartman et al. (2019) were the first to include the species a phylogenetic analysis and found it in a polytomy with Alxasaurus, Enigmosaurus and therizinosaurids. Although Glut (1997) stated this specimen may have been based on part of the holotype of Nanshiungosaurus brevispinus (based on a pers. comm from Dong to Molnar in 1984), they are from different formations and provinces. Only pedal ungual I and pedal digits II and III are illustrated by Dong, but most of the pes is illustrated in Qian et al. (2012).
The remains are about 77% as large as the referred Therizinosaurus pes, giving the taxon an approximate length of 5 meters.
References- Dong, 1979. The Cretaceous dinosaur fossils in southern China. In Institute of Vertebrate Paleontology and Paleoanthropology and Nanjing Institute of Paleontology (eds.). Mesozoic and Cenozoic Red Beds in Southern China. Science Press. 342-350.
Barsbold and Maryanska, 1990. Saurischia sedis mutabilis: Segnosauria. In Weishampel, Dodson and Osmolska (eds.). The Dinosauria. University of California Press. 408-415.
Glut, 1997. Dinosaurs - The Encyclopedia. McFarland Press. 1076 pp.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Qian, Zhang, Jiang, Jiang, Zhang, Chen and Xing, 2012. Cretaceous therizinosaurs in Zhejiang of eastern China. Journal of Geology. 36(4), 337-348.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247

Enigmosauridae Barsbold and Perle in Barsbold, 1983
Comments- Within the publication of Barsbold (1983), Enigmosauridae fam. nov. is credited to Barsbold and Perle. They placed the family in Segnosauria, separated from Segnosaurus and Erlikosaurus. This was based on several features (narrow pubis and ischium; anterior pubic symphyseal trough; narrow and elongate obturator process), which at the time simply distinguished it from Segnosaurus (Erlikosaurus' pelvis remains unknown). Enigmosaurus could be the pelvis of Erlikosaurus, but Barsbold and Perle claimed that Segnosaurus and Erlikosaurus were too similar otherwise to have such different pelves. This is not apparent, though with the new discovery of a distal humerus in the type material, comparison with Erlikosaurus is possible. Forcing Enigmosaurus and Erlikosaurus to be sister taxa in Hartman et al.'s (2019) matrix takes 4 more steps.
References- Barsbold, 1983. Carnivorous dinosaurs from the Cretaceous of Mongolia. Transactions of the Joint Soviet-Mongolian Palaeontological Expedition. 19, 117 pp.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247
Enigmosaurus Barsbold and Perle in Barsbold, 1983
E. mongoliensis Barsbold and Perle in Barsbold, 1983
Cenomanian-Santonian, Late Cretaceous
Khara Khutul, Baynshiren Formation, Mongolia
Holotype- (IGM 100/84) (~5 m; ~900 kg; old adult) dorsal ribs, sacrum, distal humerus, radius(?), proximal ulna, ventral ilia (~650 mm), pubes (634 mm), incomplete ischium (524 mm), proximal femur
Diagnosis- (after Barsbold, 1983) elongate narrow obturator process (also in Falcarius).
(after Zanno, 2010) ischial obturator processes fused.
Other diagnoses- Barsbold (1983) also listed narrow pubic and ischial shafts in his diagnosis, but these are plesiomorphic. The v-shaped anterior trough formed by the fused pubes would be matched by other therizinosaur pubes, as their pubic apron is posteriorly placed. The proximodistally shallow pubic boot is plesiomorphic for theropods, while the "shoe-like" shape is common in therizinosaurs (e.g. Nothronychus? graffami, Segnosaurus).
Barsbold and Maryanska (1990) listed the uncompressed pubic shaft in their diagnosis, but this is plesiomorphic for therizinosaurs (e.g. Falcarius, Beipiaosaurus).
The posterior pubic boot listed by Clark et al. (2004) as diagnostic is primitive for therizinosaurs.
Of Zanno's (2010) listed diagnostic characters, the subequal anterior and posterior portions of the pubic boot are primitive, being present in Falcarius and basal oviraptorosaurs for instance. The fusion of the pubic symphysis may be due to old age, as Zanno notes large amounts of resorbed bone.
Comments- Discovered prior to December 1978, the holotype was first illustrated and briefly described by Barsbold (1979) as "dinosaur from Khara Khutul." He noted it "has not yet been described and possibly represents a new family." Barsbold and Perle (1980) later described and illustrated the specimen as Segnosaurian indet.. Within the publication of Barsbold (1983), both Enigmosaurus gen. nov. and E. mongoliensis gen. et sp. nov. are credited to Barsbold and Perle. Zanno (2010) noted additional elements were present in the holotype material (dorsal ribs, distal humerus, possible radius, proximal ulna, proximal femur), as well as a large therizinosaur femoral shaft which is not referrable to the type specimen. Zanno is the first author to photograph the type material, which differs greatly from the drawing in Barsbold and Perle (1980). In particular, the pubic peduncle is anteroposteriorly narrower, the ischial peduncle more massive, the postacetabular process more complete and deeper than reconstructed, the puboischial contact is deeper, the pubic shaft is thicker and more anteriorly concave, the pubic boot is deeper, the ischial shaft is thicker, the puboischial fenestra is much shorter, the obturator process longer, and the distal ischium broken.
Currie and Eberth (1993) suggested that "There are a few elements from the Iren Dabasu that may also be referable to the more poorly known segnosaur Enigmosaurus" without evidence, but given their provenence it is more likely these are Erliansaurus, Neimongosaurus and/or the taxon represented by AMNH 6368.
Zanno (2010) recovered the taxon as closer to therizinosaurids than Erliansaurus or Neimongosaurus, but outside a clade of Suzhousaurus, Nanshiungosaurus and Nothronychus. Hartman et al. (2019), using all of Zanno's data, found it by Alxasaurus, further from therizinosaurids than Neimongosaurus or Erliansaurus. Moving it to Zanno's more derived position takes 4 steps.
Enigmosaurus mongoliensis is mostly known from itsw incomplete pelvis, which is about 95% the size of Segnosaurus' holotype. This leads to a tentative length estimate of 5 meters.
References- Barsbold, 1979. Opisthopubic pelvis in the carnivorous dinosaurs. Nature. 279, 792-793.
Barsbold and Perle, 1980. Segnosauria, a new infraorder of carnivorous dinosaurs. Acta Palaeontologica Polonica. 25(2), 187-195.
Barsbold, 1983. Carnivorous dinosaurs from the Cretaceous of Mongolia. Transactions of the Joint Soviet-Mongolian Palaeontological Expedition. 19, 117 pp.
Barsbold and Maryanska, 1990. Saurischia sedis mutabilis: Segnosauria. in Weishampel, Dodson and Osmolska (eds). The Dinosauria. University of California Press. 408-415.
Currie and Eberth, 1993. Palaeontology, sedimentology and palaeoecology of the Iren Dabasu Formation (Upper Cretaceous), Inner Mongolia, People's Republic of China. Cretaceous Research. 14, 127-144.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. in In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247

Therizinosauridae sensu Kobayashi, Takasaki, Fiorillo, Tsogtbaatar and Hikida, 2022
Definition- (Therizinosaurus cheloniformis <- Alxasaurus elesitaiensis)

Therizinosauridae Maleev, 1954
Definition- (Therizinosaurus cheloniformis + Segnosaurus galbinensis + Erlikosaurus andrewsi + Nanshiungosaurus brevispinus) (Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019; modified from Zhang et al., 2001)
Other definitions- (Erlikosaurus andrewsi <- Ornithomimus velox) (modified from Sereno, 1998)
(Erlikosaurus andrewsi <- Ornithomimus velox, Oviraptor philoceratops, Passer domesticus) (modified from Sereno, 1999)
(Therizinosaurus cheloniformis + Erlikosaurus andrewsi) (modified from Clark, Maryanska and Barsbold, 2004)
(Therizinosaurus cheloniformis + Nothronychus mckinleyi + Neimongosaurus yangi) (Sereno, online 2005)
(Therizinosaurus cheloniformis + Segnosaurus galbinensis + Erlikosaurus andrewsi + Nothronychus graffami) (Zanno, Gillette, Albright and Titus, 2009)
(Therizinosaurus cheloniformis <- Alxasaurus elesitaiensis) (Kobayashi, Takasaki, Fiorillo, Tsogtbaatar and Hikida, 2022)
= Segnosauridae Perle, 1979
= Nanshiungosauridae Dong and Yu, 1997
= "Erlikosauridae" Ryan and Russell, 2001
= Therizinosauridae sensu Clark, Maryanska and Barsbold, 2004
Definition- (Therizinosaurus cheloniformis + Erlikosaurus andrewsi) (modified)
= Therizinosauridae sensu Zanno, Gillette, Albright and Titus, 2009
Definition- (Therizinosaurus cheloniformis + Segnosaurus galbinensis + Erlikosaurus andrewsi + Nothronychus graffami)
= Therizinosauridae sensu Sereno, online 2005
Definition- (Therizinosaurus cheloniformis + Nothronychus mckinleyi + Neimongosaurus yangi)
Comments- The therizinosaurid topology here is based on the analysis of Hartman et al. (2019) which included all of the data in Zanno's extensive restudy of the group.
Maleev (1954) thought his new taxon Therizinosaurus was closely related to protostegid turtles but "the absence of a costal element of the rib, form and size of the manual claws, the great difference in the length is very distinct, which shows a complete basic appearance of the Mongolian form in a new family of turtle-like reptiles from Central Asia, Therizinosauridae..." Rozhdestvensky (1970) first recognized Therizinosaurus as theropodan, assigning Chilantaisaurus and Alectrosaurus (based on the incorrectly assigned forelimb) to Therizinosauiridae and placing the family in Carnosauria. Barsbold (1976a,b) rejected the referral of those genera, correcting the Alectrosaurus issue, and believed therizinosaurids were most similar to deinocheirids, joining them in Deinocheirosauria. However, Barsbold's classifications were more form-based than phylogenetic as evidenced by his 1983 statement "therizinosaurids are now classified within the present infraorder conditionally, only on the basis of forelimb dimensions. They may form a lineage not closely related to deinocheirids." As discussed under the Therizinosauria entry, Perle (1982) connected segnosaurids with deinocheirosaurs, placing them closer to therizinosaurids in the group, then in 1994 Russell and Dong formally synonymized the families and made therizinosaurids sister to their new family Alxasauridae in Therizinosauroidea.
Segnosauridae was established as a monotypic family of theropods by Perle (1979) until it was synonymized with Therizinosauridae by Russell and Dong (1994; see Therizinosauria entry). As the eponymous genus is an internal specifier of the current definition of Therizinosauridae, this synonymy is objective at the moment.
Dong and Yu (1997) proposed "segnosaurian dinosaurs possibly include two distinct groups. A group (Segnosauridae) is similar to the theropods, another (Nanshiungosauridae) is resembles the sauropods" without noting particular morphological characters or which genera fall into Nanshiungosauridae besides Nanshiungosaurus. The family has not been used since and the eponymous genus is an internal specifier of the current definition of Therizinosauridae.
Ryan and Russell (2001) only used Erlikosauridae in a faunal list, making it a nomen nudum (ICZN Article 13.1.1). Fossilworks.org credits Eberth et al. (2001) with Erlikosauridae, but any guidebook for the 2001 SVP meeting wouldn't be out until the meeting's date in October, whereas Olshevsky (DML, 2001) confirms Mesozoic Vertebrate Life was out by July. The family has only been used in faunal lists by authors associated with the RTMP, for frontals and a pedal ungual from the Dinosaur Park Formation assigned to Erlikosaurus sp. without merit (see entry above). While it was still used as recently as Eberth and Evans (2011), no anatomical justification was ever provided and the eponymous genus is an internal specifier of the current definition of Therizinosauridae.
References- Maleev, 1954. New turtle-like reptile in Mongolia. Priroda. 1954, 106-108.
Rozhdestvensky, 1970. Giant claws of enigmatic Mesozoic reptiles. Paleontological Journal. 1970(1), 131-141.
Barsbold, 1976a. The evolution and systematics of late Mesozoic carnivorous dinosaurs. In Kramarenko, Luvsandansan, Voronin, Barsbold, Rozhdestvensky, Trofimov and Reshetov (Eds.). Paleontology and Biostratigraphy of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition, Transactions. 3, 68-75.
Barsbold, 1976b. New data on Therizinosaurus (Therizinosauridae, Theropoda). In Kramarenko, Luvsandansan, Voronin, Barsbold, Rozhdestvensky, Trofimov and Reshetov (Eds.). Paleontology and Biostratigraphy of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition, Transactions. 3, 76-92.
Perle, 1979. Segnosauridae - A new family of theropods from the Late Cretaceous of Mongolia. Trudy - Sovmestnaya Sovetsko-Mongol'skaya Paleontologicheskaya Ekspeditsiya. 8, 45-55.
Perle, 1982. On a new finding of the hindlimb of Therizinosaurus sp. from the Late Cretaceous of Mongolia. Problems in Mongolian Geology. 5, 94-98.
Barsbold, 1983. Carnivorous dinosaurs from the Cretaceous of Mongolia. Transactions of the Joint Soviet-Mongolian Palaeontological Expedition. 19, 117 pp.
Russell and Dong, 1994. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences. 30(10), 2107-2127.
Dong and Yu, 1997. A new segnosaur from Mazongshan Area, Gansu Province, China. In Dong (ed.). Sino-Japanese Silk Road Dinosaur Expedition. China Ocean Press, Beijing. 90-95.
Sereno, 1998. A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen. 210(1), 41-83.
Sereno, 1999. The evolution of dinosaurs. Science. 284, 2137-2147.
Eberth, Currie, Brinkman, Ryan, Braman, Gardner, Lam, Spivak and Neuman, 2001. Alberta's dinosaurs and other fossil vertebrates: Judith River and Edmonton groups (Campanian-Maastrichtian). In Hill (ed.). Society of Vertebrate Paleontology, 61st Annual Meeting, Bozeman. Guidebook for the Field Trips: Mesozoic and Cenozoic Paleontology in the Western Plains and Rocky Mountains. Museum of the Rockies Occasional Paper. 3, 49-75.
Olshevsky, DML 2001. http://dml.cmnh.org/2001Jul/msg00364.html
Ryan and Russell, 2001. Dinosaurs of Alberta (exclusive of Aves). In Tanke and Carpenter (eds). Mesozoic Vertebrate Life. 279-297.
Zhang, Xu, Sereno, Kwang and Tan, 2001. A long-necked therizinosauroid dinosaur from the Upper Cretaceous Iren Dabasu Formation of Nei Mongol, People’s Republic of China. Vertebrata PalAsiatica. 39(4), 282-290.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. in In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Sereno, online 2005. Stem Archosauria - TaxonSearch. http://www.taxonsearch.org/dev/file_home.php [version 1.0, 2005 November 7]
Zanno, Gillette, Albright and Titus, 2009. A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution. Proceedings of the Royal Society B. 76(1672), 3505-3511.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Eberth and Evans, 2011. Post-Symposium Field Trip, September 24, 2011. Geology and Palaeontology of Dinosaur Provincial Park, Alberta. International Hasdrosaur Symposium. 52 pp.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247
Kobayashi, Takasaki, Fiorillo, Tsogtbaatar and Hikida, 2022. New therizinosaurid dinosaur from the marine Osoushinai Formation (Upper Cretaceous, Japan) provides insight for function and evolution of therizinosaur claws. Scientific Reports. 12:7207.

undescribed Therizinosauridae (Ikegami and Tomida, 2005)
Cenomanian-Turonian, Late Cretaceous
Amagimi Dam fossil site (Loc. 1004), Upper Layer, Mifune Group, Kumamoto, Japan
Material- (MDM coll.) parasphenoid, basisphenoid, basioccipital, exoccipital, supraoccipital, three teeth (2.3 mm), incomplete humerus, pubis (pubic boot 108 mm), partial femur
Diagnosis- (after Ikegami and Tomida, 2005) "three branched passages for the exit for the hypoglossal nerve on the postero-ventral wall of braincase unlike the other therizinosaurs but as in troodontid and ornithomimosaur, lack of a depression on the exoccipital unlike Erlikosaurus, and presence of a low nuchal crest along the midline of the supraoccipital unlike Nothronychus."
(after Ikegami et al., 2019) "pubic shaft is flattened mediolaterally and the pubic boot projects cranially and caudally."
Comments- Ikegami (2002) first reported two teeth found in 1993 and 1995, and in 2003 reported the braincase which was later CT-scanned (Ikegami and Otani, 2006). Ikegami and Tomida (2005) reported an additional tooth (from the anterior dentary) and humeral shaft, noting the latter has a posterior trochanter as in some therizinosaurids. Ikegami et al. (2019) noted the discovery of a pubis and femur, finding the former has "a fused obturator process and cranial and caudal processes which have been considered autapomorphies of Enigmosaurus." They stated "additional specimens are required to resolve whether these elements could belong to a single individual."
References- Ikegami, 2002. A therizinosauroid dinosaur from the Upper Cretaceous Mifune Group, Kumamoto Prefecture, Japan. Proceedings of the 2002 Annual Meeting of the Palaeontological Society of Japan. 129.
Ikegami, 2003. A therizinosauroid braincase from the Upper Cretaceous Mifune Group，Kumamoto Prefecrure，Japan. Palaeontological Society of Japan 2003 Annual Meeting Proceedings. 38.
Ikegami and Tomida, 2005. A therizinosaurid dinosaur from the Upper Cretaceous Mifune Group in Kyushu, Japan. Journal of Vertebrate Paleontology. 25(3), 73A.
Ikegami and Otani, 2006. 産業用x線CTスキャナーを用いた御船層群上部層産テリジノサウルス類脳函化石の内部構造の観察. Proceedings of the 155th Annual Meeting of the Palaeontological Society of Japan. 88.
Ikegami, Scannella and Tomida, 2019. Additional therizinosauroid bones collected from the Upper Cretaceous Mifune Group, Kumamoto, Japan. Journal of Vertebrate Paleontology. Program and Abstracts, 122.

unnamed Therizinosauridae (Nessov, 1981)
Late Turonian-Coniacian, Late Cretaceous
Bissekty Formation, Uzbekistan
Material- (CGMP 1980.14) anterior cervical vertebra (Britt, 1993)
(CCMGE 3/11822) tooth (Nessov, 1981)
(CCMGE 443/12457) ungual (Nessov, 1995)
(CCMGE 453/12457) ungual (Nessov, 1995)
(CCMGE 454/12457) incomplete manual ungual (Nessov, 1995)
(CCMGE 455/12457) ungual (Nessov, 1995)
(CCMGE 458/12457) centrum (Nessov, 1995)
(CCMGE 462/12457; frontal morphotype 2) frontal (81.8 mm) (Nessov, 1995)
(CCMGE 479/12457) proximal femur (Nessov, 1997)
(CCMGE 699-702/12457) manual phalanges (Nessov, 1995)
(CCMGE 704-710/12457) cervical vertebrae (Nessov, 1995)
(CCMGE 711-712/12457) anterior cervical or anterior dorsal vertebrae (Nessov, 1995)
(CCMGE 713/12457) anterior dorsal vertebra (Nessov, 1995)
(CCMGE 714/12457) posterior dorsal vertebra (Nessov, 1995)
(CCMGE 715-716/12457) distal humeri (Nessov, 1995)
(CCMGE 721-722/12457) proximal humeri (Nessov, 1995)
(IZANUz coll.) material (Sues and Averianov, 2015b)
(USNM 538146) proximal caudal neural arch (Sues and Averianov, 2015b)
(ZIN PH 16/16) (juvenile) anterior dentary (Sues and Averianov, 2015b)
(ZIN PH 18/16; frontal morphotype 1) (adult) frontal (48 mm) (Sues and Averianov, 2015b)
(ZIN PH 19/16) incomplete manual ungual (Sues and Averianov, 2015b)
(ZIN PH 27/16) metacarpal I (64.5 mm) (Sues and Averianov, 2015b)
(ZIN PH 30/16) manual phalanx I-1 (Sues and Averianov, 2015b)
(ZIN PH 31/16; humerus morphotype 2) proximal humerus (Sues and Averianov, 2015b)
(ZIN PH 34/16) distal humerus (Sues and Averianov, 2015b)
(ZIN PH 35/16) distal humerus (Sues and Averianov, 2015b)
(ZIN PH 40/16) incomplete ungual (Sues and Averianov, 2015b)
(ZIN PH 51/16) manual phalanx II-? (61.1 mm) (Sues and Averianov, 2015b)
(ZIN PH 52/16) anterior cervical vertebra (Sues and Averianov, 2015b)
(ZIN PH 53/16) manual phalanx II-? (69.5 mm) (Sues and Averianov, 2015b)
(ZIN PH 55/16) incomplete posterior cervical centrum (Sues and Averianov, 2015b)
(ZIN PH 56/16) cervical vertebra (68.5 mm) (Sues and Averianov, 2015b)
(ZIN PH 57/16) posterior cervical centrum (68.3 mm) (Sues and Averianov, 2015b)
(ZIN PH 59/16) metatarsal I (84.3 mm) (Sues and Averianov, 2015b)
(ZIN PH 64/16) pedal phalanx I-1 (Sues and Averianov, 2015b)
(ZIN PH 65/16) pedal phalanx I-1 (Sues and Averianov, 2015b)
(ZIN PH 66/16) distal metacarpal II (Sues and Averianov, 2015b)
(ZIN PH 93/16) incomplete anterior dorsal vertebra (Sues and Averianov, 2015b)
(ZIN PH 97/16) ~first or second dorsal vertebra (59.8 mm) (Sues and Averianov, 2015b)
(ZIN PH 101/16) ~second or third dorsal vertebra (Sues and Averianov, 2015b)
(ZIN PH 118/16) manual phalanx II-2/3 (Sues and Averianov, 2015b)
(ZIN PH 136/16) (juvenile) anterior cervical centrum (86.2 mm) (Sues and Averianov, 2015b)
(ZIN PH 142/16) anterior cervical vertebra (Sues and Averianov, 2015b)
(ZIN PH 266/16) tooth (Sues and Averianov, 2015b)
(ZIN PH 270/16) tooth (Sues and Averianov, 2015b)
(ZIN PH 356/16) incomplete ?pedal ungual (Sues and Averianov, 2015b)
(ZIN PH 492/16) distal metatarsal II (Sues and Averianov, 2015b)
(ZIN PH 539/16) distal metacarpal III (Sues and Averianov, 2015b)
(ZIN PH 600/16) (adult) proximal tibia (Sues and Averianov, 2015b)
(ZIN PH 615/16) sacral centrum (Sues and Averianov, 2015b)
(ZIN PH 775/16) proximal femur (Sues and Averianov, 2015b)
(ZIN PH 776/16) proximal femur (Sues and Averianov, 2015b)
(ZIN PH 777/16) (juvenile) proximal femur (Sues and Averianov, 2015b)
(ZIN PH 897/16) (juvenile) coracoid fragment (Sues and Averianov, 2015b)
(ZIN PH 978/16) (juvenile) frontal (23.8 mm) (Sues and Averianov, 2015b)
(ZIN PH 979/16; frontal morphotype 1) (adult) frontal (Sues and Averianov, 2015b)
(ZIN PH 980/16; frontal morphotype 2) (adult) frontal (Sues and Averianov, 2015b)
(ZIN PH 1001/16) incomplete proximal caudal vertebra (Sues and Averianov, 2015b)
(ZIN PH 1153/16) (juvenile) anterior dentary (Sues and Averianov, 2015b)
(ZIN PH 1154/16) dentary fragment (Sues and Averianov, 2015b)
(ZIN PH 1155/16) dentary fragment (Sues and Averianov, 2015b)
(ZIN PH 1161/16) tooth (Sues and Averianov, 2015b)
(ZIN PH 1163/16) incomplete last cervical centrum (59.5 mm) (Sues and Averianov, 2015b)
(ZIN PH 1165/16) anterior dorsal vertebra (33.5 mm) (Sues and Averianov, 2015b)
(ZIN PH 1166/16) partial posterior dorsal vertebra (Sues and Averianov, 2015b)
(ZIN PH 1167/16) posterior dorsal vertebra (Sues and Averianov, 2015b)
(ZIN PH 1177/16) manual phalanx I-1 (79.4 mm) (Sues and Averianov, 2015b)
(ZIN PH 1189/16) incomplete ?pedal ungual (Sues and Averianov, 2015b)
(ZIN PH 1195/16) distal metatarsal II (Sues and Averianov, 2015b)
(ZIN PH 1198/16) pedal phalanx II/III/IV-2/3/4 (Sues and Averianov, 2015b)
(ZIN PH 1240/16) scapulocoracoid fragment (Sues and Averianov, 2015b)
(ZIN PH 1242/16; frontal morphotype 2) (adult) frontal (Sues and Averianov, 2015b)
(ZIN PH 1243/16) maxillary fragment (Sues and Averianov, 2015b)
(ZIN PH 1244/16) manual phalanx III-1 (27.4 mm) (Sues and Averianov, 2015b)
(ZIN PH 1256/16) partial anterior cervical rib (Sues and Averianov, 2015b)
(ZIN PH 1257/16) partial anterior cervical rib (Sues and Averianov, 2015b)
(ZIN PH 1258/16) incomplete posterior cervical rib (Sues and Averianov, 2015b)
(ZIN PH 1290/16) distal humerus (Sues and Averianov, 2015b)
(ZIN PH 1348/16) distal metatarsal II (Sues and Averianov, 2015b)
(ZIN PH 1396/16) distal femoral fragment (Sues and Averianov, 2015b)
(ZIN PH 1426/16) distal tibia (Sues and Averianov, 2015b)
(ZIN PH 1428/16) distal tibia (Sues and Averianov, 2015b)
(ZIN PH 1432/16) pedal phalanx I-1 (72.5 mm) (Sues and Averianov, 2015b)
(ZIN PH 1805/16) incomplete braincase (Sues and Averianov, 2015b)
(ZIN PH 2068/16) proximal femur (Sues and Averianov, 2015b)
(ZIN PH 2214/16) distal caudal vertebra (77.4 mm) (Sues and Averianov, 2015b)
(ZIN PH 2215/16) incomplete distal caudal vertebra (Sues and Averianov, 2015b)
(ZIN PH 2216/16) incomplete distal caudal vertebra (Sues and Averianov, 2015b)
(ZIN PH 2217/16) distal caudal vertebra (Sues and Averianov, 2015b)
(ZIN PH 2220/16) distal caudal vertebra (Sues and Averianov, 2015b)
(ZIN PH 2221/16) distal caudal vertebra (Sues and Averianov, 2015b)
(ZIN PH 2237/16) incomplete posterior cervical centrum (Sues and Averianov, 2015b)
(ZIN PH 2242/16) anterior cervical prezygapophysis (Sues and Averianov, 2015b)
(ZIN PH 2274/16; humerus morphotype 1) proximal humerus (Sues and Averianov, 2015b)
(ZIN PH 2298/16) anterior cervical vertebra (80 mm) (Sues and Averianov, 2015b)
(ZIN PO 467) centrum (Nessov, 1995)
incomplete anterior dorsal vertebra (Nessov, 1997)
? distal scapulae (Sues and Averianov, 2004)
several hundred teeth, 192 elements including several sacral centra (18-75.7 mm), scapulocoracoid fragment, several coracoid fragments, three metacarpals I, distal metacarpal I, three phalanges I-1 (one fragmentary), several distal metacarpals II, six phalanges II-?, three distal metacarpals III, phalanges III-2/3 (43.7-59.6 mm), distal femoral fragment, (juvenile) proximal tibia, several distal tibiae, several metatarsals I (some fragmentary), several phalanges I-1, several phalanges II/III/IV-1 and several phalanges II/III/IV-2/3/4 (Sues and Averianov, 2015b)
Comments- A tooth (CCMGE 3/11822) originally identified as a pachycephalosaur (Nessov, 1981), was later identified as theropod (Nessov, 1997), and is therizinosauroid (Sues and Averianov, 2015). The cervical CGMP 1980.14 was described by Britt (1993) and Makovicky (1995) in their theses. Nessov (1995) was the first author to describe multiple Bissekty therizinosaur elements (as segnosaurs), though several elements were misidentified. The phalanges were said to differ from Segnosaurus and Erlikosaurus in being more elongate, but this is probably because they are manual instead of pedal (their ligament pits are reduced). The ungual CCMGE 456/12457 was figured as a segnosaur by Nessov (1995) but reassigned to Dromaeosauridae by Sues and Averianov (2014). Nessov (1995) also tentatively referred a basisphenoid fragment (CCMGE 719/12457) to a segnosaur, but Sues and Averianov (2015) stated it was "too fragmentary for more precise taxonomic identification beyond Theropoda." A caudal (CCMGE 725/12457) referred to cf. Dryptosaurus, Segnosauria or cf. Hypsibema by Nessov (1995) turns out to be ornithomimid (Sues and Averianov, 2015a). Nessov (1995) figured a centrum (CCMGE 458/12457) as "a theropod(?) or a large non-flying bird", which was reidentified as therizinosauroid by Sues and Averianov (2015b). The braincase CCMGE 628/12457 was originally referred to Turanoceratops by Nessov (1995), reidentified by Sues and Averianov (2004) as therizinosauroid, and finally described as titanosaurian by Sues et al. (2015). A dorsal vertebra was figured as Sauropoda indet. by Nessov (1997), but is therizinosauroid (Sues and Averianov, 2015b). Sues and Averianov (2004) first reported proximal and distal scapulae (though no distal scapulae are noted by Sues and Averianov, 2015b). Sues and Averianov (2015b) describe the Bissekty therizinosaur material in detail.
Averianov (2007) first noted multiple taxa are represented, which was expanded on by Sues and Averianov (2015b). Specifically, two frontal and humeral morphologies are present. They included the Bissekty material in a version of Zanno's TWiG analysis and found the chimaeric OTU to be closer to Therizinosaurus than Alxasaurus, but outside the clade containing Erliansaurus, Neimongosaurus and Therizinosauridae. When added to Hartman et al.'s coelurosaur matrix, the OTU emerges in the Suzhousaurus plus Therizinosaurus clade of therizinosaurids.
References- Nessov, 1981. Cretaceous salamanders and frogs of Kyzylkum Desert. Trudy Zoologicheskogo Instituta AN SSSR 101, 57-88.
Britt, 1993. Pneumatic postcranial bones in dinosaurs and other archosaurs. PhD Thesis, University of Calgary (Canada), Alberta.
Makovicky, 1995. Phylogenetic aspects of the vertebral morphology of Coelurosauria (Dinosauria: Theropoda). M.S. thesis, Copenhagen University, Copenhagen, Denmark.
Nessov, 1995. Dinosaurs of Northern Eurasia: new data about assemblages, ecology and paleobiogeography. Scientific Research Institute of the Earth's Crust, St. Petersburg State University, St. Petersburg, Russia. 156 pp. + 14 pl.
Sues and Averianov, 2004. Dinosaurs from the Upper Cretaceous (Turonian) of Dzharakuduk, Kyzylkum Desert, Uzbekistan. Journal of Vertebrate Paleontology. 24(3), 51A-52A.
Averianov, 2007. Theropod dinosaurs from Late Cretaceous deposits in the northeastern Aral Sea region, Kazakhstan. Cretaceous Research. 28(3), 532-544.
Sues and Averianov, 2014. Dromaeosauridae (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan and the phylogenetic position of Itemirus medullaris Kurzanov, 1976. Cretaceous Research. 51, 225-240.
Sues and Averianov, 2015a. Ornithomimidae (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan. Cretaceous Research. 57, 90-110.
Sues and Averianov, 2015b. Therizinosauroidea (Dinosauria: Theropoda) from the Upper Cretaceous of Uzbekistan. Cretaceous Research. 59, 155-178.
Sues, Averianov, Ridgely and Witmer, 2015. Titanosauria (Dinosauria, Sauropoda) from the Upper Cretaceous (Turonian) Bissekty Formation of Uzbekistan. Journal of Vertebrate Paleontology. 35(1), e889145.

Suzhousaurus Li, Peng, You, Lamanna, Harris, Lacovata and Zhang, 2007
S. megatherioides Li, Peng, You, Lamanna, Harris, Lacovata and Zhang, 2007
Late Aptian, Early Cretaceous
Middle Gray-variegated Beds of the Xiagou Formation, Gansu, China
Holotype- (FRDC-GSJB-99) ten incomplete to complete dorsal vertebrae, several incomplete dorsal ribs, incomplete scapulocoracoid (scap ~705 mm), humerus (550 mm), (?)ilial fragment, incomplete pubes, fragments
Early Albian, Early Cretaceous
Upper Red Beds of the Zhonggou Formation, Gansu, China
Referred- (FRDC-GSJB-2004-001) eighth dorsal vertebra (115 mm), ninth dorsal vertebra (115 mm), tenth dorsal vertebra (117.5 mm), seven dorsal ribs, sacrum (80, 90, 115, 105, 100 mm), first caudal vertebra (87.5 mm), second caudal vertebra (87.5 mm), third caudal vertebra (82.5 mm), fourth caudal vertebra (90 mm), fifth caudal vertebra (97.5 mm), sixth caudal vertebra (97.5 mm), six chevrons, ilium (~790 mm), incomplete pubis (~670 mm), ischium (660 mm), femora (one partial; 840 mm) (Li et al., 2008)
Aptian-Albian, Early Cretaceous?
Xiagou or Zhonggou Formations, Gansu, China?
? dentary tooth (Button et al., 2015)
Diagnosis- (after Li et al., 2008) transversely expanded distal ends of sacral and proximal caudal neural spines (possibly in Nanshiungosaurus); preacetabular process of ilium straight and untwisted in dorsal/ventral view.
Other diagnoses- Li et al. (2007) listed a pubis with a strongly concave anterior margin as an apomorphy, but this is also present in Segnosaurus (Zanno, 2010; contra earlier illustrations) and Nothronychus? graffami. Zanno notes the glenoid is damaged, so the poor demarcation noted by Li et al. cannot be confirmed. Further, she notes the "prominent rounded and striated tumescence on the dorsomedial surface of its scapular portion" is common in derived therizinosaurs.
Li et al. (2008) also listed posterior dorsal spine tables in their diagnosis, but these are also present in Falcarius (though that taxon lacks caudal spine tables) and possibly Nanshiungosaurus. Lateral deflection of the preacetabular process is present in all therizinosauroids, nor does the blade seem particularily thin compared to Neimongosaurus for instance. But the flatness is diagnostic compared to the twisted blades in taxa such as Falcarius and Segnosaurus. The preacetabular process has a smoothly rounded anterodorsal edge in Beipiaosaurus, Nanshiungosaurus, Nothronychus? graffami, and probably Segnosaurus (Zanno, 2010; contra earlier illustrations).
Comments- The holotype was discovered in 1999 and officially described by Li et al. (2007) a few months before the SVP abstract about it and the referred specimen (found in 2004) was published by Lamanna et al. (2007). The referred specimen was later described by Li et al. (2008). Suzhousaurus cannot be compared with "Nanshiungosaurus" bohlini from the same stratigraphic group, and may be synonymous. If they are indeed synonymous, Li et al. (2007) note the correct name will be Suzhousaurus bohlini.
References- Li, Peng, You, Lamanna, Harris, Lacovata and Zhang, 2007. A large therizinosauroid (Dinosauria: Theropoda) from the Early Cretaceous of northwestern China. Acta Geologica Sinica (English Edition). 81(4), 539-549.
Lamanna, You, Li, Peng and Harris, 2007. A new large-bodied therizinosauroid (Dinosauria: Theropoda) from the Early Cretaceos of Northwestern China. Journal of Vertebrate Paleontology. 27(3), 103A.
Li, 2008. Therizinosauroid dinosaurs from the Early Cretaceous of Yujingzi Basin, Jiuquan area, Gansu Province, China. PhD thesis, China University of Geosciences. [pp]
Li, You and Zhang, 2008. A new specimen of Suzhousaurus megatherioides (Dinosauria: Therizinosauroidea) from the Early Cretaceous of northwestern China. Canadian Journal of Earth Sciences. 45, 769-779.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Button, Zanno, You and Kirkland, 2015. Dichotomous evolution of tooth growth and replacement strategies in herbivorous dinosaurs. Journal of Vertebrate Paleontology. Program and Abstracts 2015, 100.
You, Morschhauser, Li and Dodson, 2018. Introducing the Mazongshan dinosaur fauna. Journal of Vertebrate Paleontology. 38(supp. 1), 1-11.

Neimongosaurus Zhang, Xu, Sereno, Kwang and Tan, 2001
N. yangi Zhang, Xu, Sereno, Kwang and Tan, 2001
Middle-Late Campanian, Late Cretaceous
Sanhangobi, Iren Dabasu Formation, Inner Mongolia, China
Holotype- (LH V0001) (2.33 m; 90 kg) partial braincase, anterior dentary, axis (~55 mm), third cervical vertebra (55 mm), fourth cervical vertebra (65 mm), fifth cervical vertebra (72 mm), sixth cervical vertebra (72 mm), seventh cervical vertebra (72 mm), eighth cervical vertebra (72 mm), ninth cervical vertebra (72 mm), tenth cervical vertebra (72 mm), eleventh cervical vertebra (72 mm), twelfth cervical vertebra (47 mm), thirteenth cervical vertebra (47 mm), fourteenth cervical vertebra (31 mm), several cervical ribs, first dorsal vertebra (~35 mm), second dorsal vertebra (~35 mm), third dorsal vertebra (40 mm), fourth dorsal vertebra (40 mm), fifth dorsal vertebra, sixth dorsal vertebra, seventh dorsal vertebra, eighth dorsal vertebra, sacrum, first caudal vertebra (39 mm), second caudal vertebra (38 mm), third caudal vertebra (35 mm), fourth caudal vertebra (38 mm), fifth caudal vertebra (39 mm), sixth caudal vertebra (38 mm), seventh caudal vertebra (38 mm), eighth caudal vertebra (38 mm), ninth caudal vertebra (36 mm), tenth caudal vertebra (36 mm), eleventh caudal vertebra (34 mm), twelfth caudal vertebra (33 mm), thirteenth caudal vertebra (31 mm), fourteenth caudal vertebra (31 mm), fifteenth caudal vertebra (31 mm), sixteenth caudal vertebra (28 mm), seventeenth caudal vertebra (28 mm), eighteenth caudal vertebra (26 mm), nineteenth caudal vertebra (22 mm), twentieth caudal vertebra (22 mm), twenty-first caudal vertebra (18 mm), twenty-second caudal vertebra (13 mm), several chevrons, partial scapulocoracoids, furcula (128 mm), humeri (222 mm), radius (180 mm), partial ilia, femora (366 mm), tibiae (310 mm), distal tarsal III, distal tarsal IV, metatarsal I (57 mm), phalanx I-1 (33 mm), metatarsal II (116 mm), phalanx II-1 (30 mm), phalanx II-2, metatarsal III (120 mm), phalanx III-1 (27 mm), phalanx III-2, phalanx III-3, metatarsal IV, phalanx IV-1 (27 mm), phalanx IV-2, phalanx IV-3, partial metatarsal V
Paratype- (LH V0008) sacrum, ilia
Diagnosis- (after Zhang et al., 2001) radius with a prominent biceps tuberosity; tibia with an extremely long fibular crest that ends at over 50% the length of the tibia (also in Nothronychus? graffami).
(proposed) distal humerus expanded more than three times shaft width.
Other diagnoses- Most of Zhang et al.'s (2001) listed diagnostic characters are more widely distributed, as noted by Zanno (2010). In particular, Zanno stated the distal caudal prezygapophyses were not more divergent than other therizinosaurs, based on unpublished data probably referring to Nothronychus? graffami. Proximal caudal vertebrae with a fossa ventral to the transverse process are also known in Nothronychus mckinleyi and N? graffami, as well as oviraptorosaurs such as Nomingia. The lateral surface of the preacetabular process is twisted dorsally in most therizinosaurs (e.g. Falcarius, Nothronychus? graffami, Segnosaurus). The fibular crest of the tibia is not significantly more elongate (57%) than in Nothronychus? graffami (55%), though is longer than Nothronychus mckinleyi (50%), Segnosaurus and Erliansaurus (both 48%). Proximal pedal phalanges with well developed heels are present in Erlikosaurus, Therizinosaurus, Nothronychus mckinleyi and N? graffami.
Comments- The type material was discovered in 1999.
Neimongosaurus has an almost complete vertebral column preserved, assuming 22 presacrals like Nanshiungosaurus. The fourteen cervicals are 804 mm long, the eight dorsals are 315 mm and the estimated 28 caudals are about 755 mm (it appears about six are missing). Though no sacral measurements are given, both the last dorsal and the first caudal are about 40 mm. Estimating for Neimongosaurus' six sacral vertebrae leads to a length of 240 mm. Assuming the skull is about 95% of humeral length (93% in Erlikosaurus, 98% in Alxasaurus), that means a 211 mm long skull. These all total to 2.33 meters.
References- Zhang, Xu, Sereno, Kwang and Tan, 2001. A long-necked therizinosauroid dinosaur from the Upper Cretaceous Iren Dabasu Formation of Nei Mongol, People’s Republic of China. Vertebrata PalAsiatica. 39(4), 282-290.
Burch, 2006. The range of motion of the glenohumeral joint of the therizinosaur Neimongosaurus yangi (Dinosauria: Theropoda). Journal of Vertebrate Paleontology. 27(3), 46A.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

Erliansaurus Xu, Zhang, Sereno, Zhao, Kuang, Han and Tan, 2002
E. bellamanus Xu, Zhang, Sereno, Zhao, Kuang, Han and Tan, 2002
Middle-Late Campanian, Late Cretaceous
Sanhangobi, Iren Dabasu Formation, Inner Mongolia, China
Holotype- (LH V0002) (~2.57 m; 120 kg; subadult) mid cervical vertebra (61 mm), posterior cervical vertebra (50 mm), anterior dorsal vertebra (45 mm), two proximal caudal vertebrae (50, 47 mm), scapula (227 mm), humerus (276 mm), radius (220 mm), ulna (237 mm), metacarpal I (57 mm), phalanx I-1 (58 mm), manual ungual I (91 mm), metacarpal II (116 mm), phalanx II-1 (40 mm), phalanx II-2 (45 mm), manual ungual II (~76 mm), metacarpal III (79 mm), phalanx III-1 (17 mm), phalanx III-2 (14 mm), phalanx III-3 (33 mm), manual ungual III, partial ilium, pubic fragments, ischial fragments, femur (412 mm), tibiae (373 mm), fibula (~350 mm), partial metatarsals
Diagnosis- (after Xu et al., 2002) enlarged nutrient foramen on proximal caudal vertebrae; crest-like posterior trochanter on humerus; anterior margin of proximal tibia significantly higher than posterior margin; distally located hypertrophied iliofibularis tubercle on fibula (also in Nothronychus?).
(proposed) manual phalanges of digit II each shorter than 40% of metacarpal II length.
Other diagnoses- Xu et al. note the presence of an oval fossa by the posterior humeral trochanter, but this is present in other therizinosaurs as well (e.g. Falcarius, Neimongosaurus- Zanno, 2008). Zanno (2010) believes the supposed supratrochanteric process on the ilium is merely the anterior portion of the postacetabular tuber present in derived therizinosaurs, as the ilium is crushed and poorly preserved. Xu et al. note Nothronychus and Segnosaurus also have a distally placed m. iliofibularis tubercle on their fibula, but state Erliansaurus' is larger. Zanno states Nothronychus also has a hypertrophied tubercle, but the issue cannot be resolved with current illustrations.
Comments- The holotype was discovered in 1999.
Erliansaurus bellamanus has wonderful appendicular preservation, but very few known vertebrae. The mid-cervical vertebra is actually shorter than Neimongosaurus' (~85%), indicating a much shorter neck proportionately, as all other dimensions are larger (appendicular elements 13-24% larger). The cervical series was approximately 680 mm, assuming a similar number of cervicals. The anterior dorsal centrum is 13% larger than Neimongosaurus', giving a dorsal length estimate of 355 mm. A sacrum about 20% larger than Neimongosaurus' would be about 290 mm long. The proximal caudal centrum resembles the third of Neimongosaurus and is about 1.32 times as long, suggesting a tail length of 990 mm. Finally, the skull was probably about 255 mm long, judging by the humeral length. Thus, Erliansaurus was approximately 2.57 meters.
References- Xu, Zhang, Sereno, Zhao, Kuang, Han and Tan, 2002. A new therizinosauroid (Dinosauria, Theropoda) from the Upper Cretaceous Iren Dabau Formation of Nei Mongol. Vertebrate Palasiatica. 40(3), 228-240.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

Paralitherizinosaurus Kobayashi, Takasaki, Fiorillo, Tsogtbaatar and Hikida, 2022
P. japonicus Kobayashi, Takasaki, Fiorillo, Tsogtbaatar and Hikida, 2022
Early Campanian, Late Cretaceous
Nakagawa, Osoushinai Formation, Yezo Group, Hokkaido, Japan
Holotype- (NMV-52) cervical central fragment, metacarpal I (57.87 mm), proximal manual ungual ?I, proximal manual ungual ?II, incomplete manual ungual ?III (~170 mm)
Diagnosis- (after Kobayashi et al., 2022) dorsoventrally flattened metacarpal I (dorsoventral height less than half of transverse width) with no rotation of the axis of the distal end; proximodorsal lip in manual unguals II and III (also in Falcarius); shallow depression at proximoventral side of of manual ungual III, connecting to the collateral groove (also in Nothronychus and Therizinosaurus); proximally extending ventral process (also in Erliansaurus and Therizinosaurus); weak flexor tubercle expressed as small ridge (also in Therizinosaurus).
Other diagnoses- Note Kobayashi et al. (2022) listed "presence of proximodorsally projecting dorsal lip in digits I and III", but this is a typo for II and III as the proximodorsal edge of I is unpreserved.
Comments- Discovered in September 2000, Murakami et al. (2012) described this as Maniraptora gen. et sp. indet. based on the proximodorsal lips on its manual unguals. They further noted it shared a character with Therizinosaurus, the lack of a groove between flexor tubercle and articular surface on at least some unguals, which "potentially suggests that this specimen belongs to a derived therizinosauroid." Kobayashi et al. (2022) redescribed the specimen, identifying a vertebral fragment and reinterpreting the dorsal edge of manual ungual I to be broken and thus not necessarily lipped proximally. They added it to a version of Zanno's TWiG analysis, recovering it in a polytomy with other therizinosaurids. Paralitherizinosaurus falls out sister to Falcarius if scored in Hartman et al.'s maniraptoromorph matrix, but can fall out elsewherte in Therizinosauria outside the Segnosaurus+Nothronychus clade with a single step. It is placed sister to Therizinosaurus here based on the ungual similarities not scored for in these analyses.
References- Murakami, Hirayama, Hikida and Hirano, 2008. A theropod dinosaur (Saurischia: Maniraptora) from the Upper Cretaceous Yezo Group of Hokkaido, northern Japan. Paleontological Research. 12(4), 421-425.
Kobayashi, Takasaki, Fiorillo, Tsogtbaatar and Hikida, 2022. New therizinosaurid dinosaur from the marine Osoushinai Formation (Upper Cretaceous, Japan) provides insight for function and evolution of therizinosaur claws. Scientific Reports. 12:7207.

Therizinosaurus Maleev, 1954
T. cheloniformis Maleev, 1954
Early Maastrichtian, Late Cretaceous
Nemegt, Nemegt Formation, Mongolia
Holotype- (PIN 551-483) (~8.2 m; ~3.9 tons) several dorsal rib fragments, proximal manual ungual I, incomplete manual ungual II (~655 mm), incomplete manual ungual III (~500 mm), metatarsal(?) (270 mm),
Referred- (IGM 100/15) (9.6 m; ~6.2 tons) dorsal rib fragments, gastralial fragments, scapulocoracoids (one fragmentary; scapula 670 mm, coracoid 360 mm), humeri (760 mm), radii (550.4 mm), ulna (620.2 mm), distal carpal I, distal carpal II, metacarpal I (145.5 mm), metacarpal II (286.8 mm), phalanx II-1 (141.7 mm), phalanx II-2 (145.8 mm), manual ungual II (~585 mm), metacarpal III (191.6 mm) (Barsbold, 1976)
Early Maastrichtian, Late Cretaceous
Altan Uul, Nemegt Formation, Mongolia
(IGM 100/17; lost?) proximal manual ungual ?III (~435 mm) (Barsbold, 1976)
Early Maastrichtian, Late Cretaceous
Upper White Beds of Khermeen Tsav, Mongolia
(IGM 100/16; lost?) distal manual ungual ?I (Barsbold, 1976)
?(IGM 100/45; lost?) (~6.5 m; ~1.9 tons) femoral fragments, tibial fragments (distal end 253 mm wide), astragalus, calcaneum, distal tarsal IV, proximal metatarsal I, distal phalanx I-1, proximal pedal ungual I, metatarsal II (200 mm), phalanx II-1 (85 mm), phalanx II-2 (95 mm), metatarsal III (250 mm), phalanx III-2 (~64.9 mm), proximal pedal ungual III, proximal metatarsal IV, phalanx IV-1 (70 mm), phalanx IV-2 (30 mm), phalanx IV-3 (33 mm), phalanx IV-4 (~65 mm) (Perle, 1982)
Diagnosis- (after Maleev, 1955) large size; hypertrophied manual unguals, longer than four times proximal height; manual unguals highly compressed transversely (<20% of dorsoventral height).
(after Barsbold, 1976) humerus with hypertrophied deltopectoral crest, exceeding 60% of humeral length; deep incision into lateral margin of distal carpal I; manual unguals very slightly curved; manual unguals with only slight decrease in height distally.
(after Clark et al., 2004) distal carpals partially fused to metacarpals I and II.
(after Zanno, 2010) enlarged medial longitudinal crest on metacarpal I; manual ungual I nearly flat ventrally in lateral view.
Other diagnoses- Maleev's (1955) original diagnosis was based on comparison to protostegids, so included the absence of dorsal armor, which is of course plesiomorphic for theropods. However, the body was probably not broad and depressed, and the "nearly derived forelimbs" are too ambiguous to evaluate.
Barsbold (1976) listed many additional characters. The short scapular blade is probably caused by a missing distal end, while the "elongated ventral expansion" of the scapulocoracoid, whether referring to the acromion of posteroventral coracoid process, is primitive for therizinosaurs. The distal humerus is expanded more in Neimongosaurus. The untwisted humerus and sigmoid radial shaft are found in several other therizinosaurs. The olecranon fossa of the ulna (described as semilunate) seems to be shaped similarly to that of Falcarius. The semilunate distal carpus is plesiomorphic for therizinosaurs. The first metacarpal is shortest and dorsoventrally flattened, second longest, and third most slender in all therizinosaurs. The manual phalanges are comparatively longer than in Erliansaurus.
Of Zanno's (2010) characters, Erliansaurus and Nothronychus? graffami also have metacarpal I over 66% of metacarpal III length (72% and 75% respectively vs. 76% in Therizinosaurus). Zanno says Therizinosaurus' manual unguals lack ventrally projecting flexor tubercles, but that on ungual II is comparable to those of Erliansaurus in extending to the proximal ungual edge and only having a low ventral corner. Manual ungual I does have an extremely reduced ventral corner however, giving the illusion of a non-projected flexor tubercle.
Comments- The holotype (PIN 551-483) was discovered in 1948 and described by Maleev in 1954 as a new taxon of turtle, related to protostegids. It consists of rib fragments, a metacarpal and three incomplete manual unguals. Maleev illustrated a rib fragment and ungual, while Rozhdestvensky (1970) illustrated all three unguals. Rozhdestvensky reidentified the metacarpal as a metatarsal (he writes metatarsus, but Maleev described a single element), and referred both it and the ribs to Sauropoda without justification. The dorsal rib fragments are described as having T-shaped to triangular sections, which differs from the round sections in titanosaurs and embryonic therizinosaurs. Unfortunately, no adult therizinosaur ribs have had their cross sections described yet, though some theropods are known to have T-shaped sections (e.g. Tugulusaurus). Notably, the photographed ribs of Suzhousaurus suggest they have a longitudinal ridge that could indicate a T-shaped section. However, Barsbold (1976) states the rib fragments found with IGM 100/15 are more slender than those found with the holotype. This may indicate the ribs do not belong to Therizinosaurus, or that different sections or positions of rib were preserved with each specimen. The metapodial is described as 270 mm long, which is close in size to metacarpal II in IGM 100/15, but too short to be any metatarsal except metatarsal I unless Therizinosaurus had a much shorter pes than Nothronychus? graffami. The reported dorsoventral width of the proximal end (20 mm) is too small to be any metapodial, except perhaps metatarsal I, which only has a narrow contact with the tarsus. The cylindrical distal condyle resembles metatarsals more than the ginglymoid metacarpals of therizinosaurs. This may therefore be a metatarsal I, but the narrow proximal dimension of metatarsal I in Therizinosaurus is transverse instead of dorsoventral, and the "short, low crest" present on the dorsal surface mentioned by Maleev is of unknown homology. Metacarpals of titanosaurs differ in lacking distal condyles, with both sauropod metacarpals and metatarsals are too deep proximally to match Maleev's measurements. There seems to be no reason to suggest it is a sauropod metatarsal instead of a therizinosaur metatarsal, and Rozhdestvensky could have been easily confused by the derived morphology of therizinosaurs (stout metatarsals with wide ends) which is somewhat sauropod like.
The referred specimen IGM 100/15 was discovered in 1973 and includes pectoral girdles, forelimbs (missing digits I and III), dorsal ribs and gastralia (Barsbold, 1976). The forelimb is proportioned very much like Nothronychus, and is about 1.8 times larger, leading to a length of 9.6 meters. The holotype is about 85% as large, so 8.2 meters long. Another proximal end of a manual ungual (IGM 100/17) was found in 1968 and identified as belonging to digit III by Barsbold. Another referred manual ungual (IGM 100/16) was found in 1972 and referred to digit I by Barsbold. As it lacks the proximal portion, it cannot be measured accurately. The hindlimb specimen (IGM 100/45) was also discovered in 1973 but is not directly comparable (Perle, 1982), so is referred only tentatively. It is actually only 94% as large as Segnosaurus specimen IGM 100/82, so would be about 6.5 meters long. This specimen was illustrated in figure 18.2K of Barsbold and Maryanska's (1990) segnosaur chapter as segnosaurid indet.. Zanno (2010) states the IGM material is all lost but there are photos on Wikipedia of the mounted specimen so this is untrue for 100/15 at least.
References- Maleev, 1954. New turtle-like reptile in Mongolia. Priroda. 1954, 106-108.
Rozhdestvensky, 1970. Giant claws of enigmatic Mesozoic reptiles. Paleontological Journal. 1970(1), 131-141.
Barsbold, 1976. New data on Therizinosaurus (Therizinosauridae, Theropoda). In Kramarenko, Luvsandansan, Voronin, Barsbold, Rozhdestvensky, Trofimov and Reshetov (eds.). Paleontology and Biostratigraphy of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition, Transactions. 3, 76-92.
Perle, 1982. On a new finding of the hindlimb of Therizinosaurus sp. from the Late Cretaceous of Mongolia. Problems in Mongolian Geology. 5, 94-98.
Barsbold and Maryanska, 1990. Saurischia sedis mutabilis: Segnosauria. in Weishampel, Dodson and Osmolska (eds). The Dinosauria. University of California Press. 408-415.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

unnamed therizinosaurid (Manning, Joysey and Cruikshank, 1997)
Santonian-Campanian, Late Cretaceous
Nanchao Formation, Henan, China
Material- (CAGS-01-IG-1; = RAP 194D) incomplete skull, mandible, vertebrae, three manual unguals, egg
(CAGS-01-IG-2; = RAP 3495D) (embryo) egg, parabasisphenoid, two metacarpals, partial femora, partial tibiae, metatarsal, fragments
(CAGS-01-IG-4; = RAP 3494D) (embryo) egg, posterior dorsal centrum, dorsal neural arch, humerus, ulna, femur, tibia, fragments
(CAGS-01-IG-5; = RAP 10495D) (embryo) egg, atlantal centrum, atlantal arch, axis, third cervical vertebra, fourth cervical vertebra, fifth cervical vertebra, cervical ribs, several dorsal vertebrae, six dorsal ribs, scapula, humerus, radius, ulna, pubes, incomplete ischia, partial femur, partial tibiae, fibula, metatarsal
(CAGS-01-IG-7; = RAP 7294D) (embryo) egg, fragments
(CAGS-01-IG-11; = RAP 1294D) (embryo) egg, fragments
(CAGS-01-IG-12; = RAP 294D) (embryo) egg, dorsal centra, dorsal neural arch, dorsal rib, humerus, ilium, fragments
(CAGS-01-IG-13) nest of seven eggs
....(RAP 596D) egg
....(RAP 696D) egg
....(RAP 796D) (embryo) egg, elements
....(RAP 1196D) (embryo) egg, elements
....(CAGS-01-IG-6; = RAP 1496D) (embryo) egg, parabasisphenoid, two cervical centra, anterior dorsal centrum, two dorsal rib, mid caudal vertebra, coracoid, furcula, partial ilium, two pedal unguals, fragments
(RAP 195D) egg
(RAP 896D) egg
(RAP 1094D) egg
(RAP 1096D) egg
(RAP 2395D) egg
(RAP 10494D) disarticulated skull and partial postcrania, egg
Comments- The eggs are dendroolithid.
Sigogneau-Russell et al. (1998) referenced RAP 194D to compare its tooth size to isolated theropod teeth from the Berriasian of Anoual, Morocco. This was misinterpreted by Ford (www.paleofile.com) as a reference to a Moroccan therizinosaur egg and embryo.
Hartman et al. (2019) were the first authors to include these embryos in a phylogenetic analysis, recovering them as therizinosaurids just basal to a Nanshiungosaurus plus Segnosaurus clade.
References- Cohen, Cruickshank, Joysey, Manning and Upchurch, 1995. The Dinosaur Egg and Embryo Project. Exhibition Guide. Rock Art, Leicester.
O'Brien, 1995. Dinosaur embryos spark exitement, concern. Science. 267, 1760.
Manning, Joysey and Cruikshank, 1997. Observations of microstructures within dinosaur eggs from Henan Province, Peoples Republic of China. in Wolberg, Stump and Rosenburg eds. Dinofest International: Proceedings of a Symposium held at Arizona State University. Philadelphia: Academy of Sciences. 287-290.
Sigogneau-Russell, Evans, Levine and Russell, 1998. The Early Cretaceous microvertebrate locality of Anoual, Morocco: A glimpse at the small vertebrate assemblages of Africa. in Lucas, Kirkland and Estep (eds.). Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Mesuem of Natural History and Science. 14, 177-181.
Manning, Joysey and Cruikshank, 2000. In ovo tooth replacement in a therizinosaurid dinosaur. First International Symposium on Dinosaur Eggs and Babies. Extended Abstracts. 129-134.
Kundrát, Cruickshank, Manning and Joysey, 2001. Structure of the embryonic parabasisphenoid in a therizinosauroid dinosaur. Journal of Morphology. 248(3), 251-252.
Kundrát, Cruickshank, Manning and Nudds, 2004. Therizinosauroid affinities within maniraptoriform theropods based on embryonic data. EAVP 2, abstracts, pg. 20.
Kundrát, Cruickshank, Manning and Nudds, 2007. Embryos of therizinosauroid theropods from the Upper Cretaceous of China: Diagnosis and analysis of ossification patterns. Acta Zoologica. 89(3), 231-251.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247

Nanshiungosaurus Dong, 1979
N. brevispinus Dong, 1979
Late Cretaceous
IVPP locality 74015, Nanxiong Group, Dapingcun, Guangning County, Guangdong, China
Holotype- (IVPP V4731) (~4.40 m; 600 kg) axis (135 mm; lost), third through twelfth cervical vertebrae (1.27 m; twelfth cervical 76 mm; all lost), first through tenth dorsal vertebrae (730 mm; lost), sacrum (six vertebrae- 680 mm), first caudal vertebra (lost), incomplete ilium (726 mm), proximal pubis, proximal ischia (474 mm)
Diagnosis- (after Dong, 1979) twelve cervical vertebrae; highly elongate cervical vertebrae (2.5 times length of dorsal centra) (also in Nothronychus mckinleyi); opisthocoelous posterior cervical centra; ten dorsal vertebrae (unknown in other therizinosaurs more derived than Beipiaosaurus); sacral spine tables (also in Suzhousaurus); sacral neural spines with saddle shaped depressions on apex; narrow, elongate preacetabular process (also in Nothronychus? graffami).
(after Clark et al., 2004) proximal puboischial contact much deeper than acetabulum.
(proposed) ventral edge of preacetabular process cenvex.
Other diagnoses- As Nanshiungosaurus was originally identified as a sauropod by Dong (1979), most of the diagnostic character he listed are now known to be plesiomorphic for therizinosaurs- short neck compared to sauropods; platycoelous anterior cervical centra; cervical pleurocoels poorly developed compared to sauropods; low cervical neural spines; cervical neural spines not bifid; platycoelous dorsal centra; dorsal centrum height and length subequal; dorsal pleurocoels shallow compared to sauropods; low and broad dorsal neural spines; short sacral neural spines; sacral neural spines fused into lamina; low ilium compared to sauropods; pubis not twisted; obturator foramen absent in pubis; thick lateral margin of pubis (as contrasted to the pubic apron); plate-like ischium; fused ischial symphysis. The presence of ten dorsal vertebrae is less than the at least twelve present in Beipiaosaurus, but is unknown in other more derived therizinosaurids. Dorsal neural spine tables are also present in Falcarius and Suzhousaurus. Zanno (2010) notes there are actually six sacral vertebrae in Nanshiungosaurus, not five as described by Dong. The pubic peduncle of the ilium is neither straight nor robust. The expanded distal ischium is near certainly the obturator process and mid dorsal process as found in other therizinosaurs, with the narrow distal tip broken off.
Comments- Nanshiungosaurus was originally identified by Dong (1979) as a titanosaurine (titanosaurian in modern usage) sauropod closest to Titanosaurus itself, but stated "the two are so distinct that it is obvious the Nanxiong specimen belongs to a new clade." It was still considered a sauropod by Paul (1984), but by 1988 he had illustrated it as a segnosaur, both without comment. The first justified referral to Segnosauria was by Maryanska and Barsbold (1990), who noted "an opisthopubic pelvis that is very similar to that of S. galbinensis" and that "the structure of cervical vertebrae in N. brevispinus is similar to that in the Mongolian segnosaurians."
Zanno (2010) notes much material is lost, and the pelvis is less complete than when described by Dong.
The stratigraphic nomenclature has been controversial with Zhao et al.'s 1991 scheme dividing the Nanxiong into a lower Yuanpu Formation (which Zanno, 2010 placed Nanshiungosaurus in) and an upper Pingling Formation (which Russell et al., 1993 placed Nanshiungosaurus in when they said "Rare skeletal remains in the Pingling Formation indicate the presence of ... therizinosaurids" and cite Dong, 1979; note Le Loeuff 2012 didn't realize this and thought Russell et al.'s therizinosaurid remains were different). The Guangdong Geological Survey Institute's 2017 stratigraphic nomenclature replaces the Yuanpu Formation with the Dafeng Formation, which has been suggested to be Cenomanian-Middle Campanian by Xi et al. 2021 and which Ke et al. (2023) assigned Nanshiungosaurus to. If Russell et al. were correct in placing Nanshiungosaurus in the Pingling Formation, that's now known as the Zhenshui Formation which Xi et al. assign to the Early Maastrichtian. Its stratigraphic level is shown in Figure 2 section 10 number 11 of Mateer and Chen (1992).
One potential problem with size estimates for this species is that both the line drawings and the plates are said to be at 1/4 size, but the plates are 1.7 times larger. The line drawing scale is correct, as shown by two pieces of evidence. First, Russell and Dong (1994) estimate Nanshiungosaurus' mass as 1.5 tons, compared to Segnosaurus' 1.9 tons. The pelvis of Segnosaurus (GM 100/80) and Nanshiungosaurus are similar in size assuming the smaller size estimate, with two other Segnosaurus specimens being slightly larger. Russell and Dong's mass estimates make sense in this case. If Nanshiungosaurus were 1.7 times larger though, it would also be 1.7 times larger than Segnosaurus' holotype. It would then be almost 5 times heavier, putting the mass estimate at over 9 tons. Second, Dong and Yu (1997) diagnosed Nanshiungosaurus? bohlini as being larger than any known segnosaur. The first dorsal vertebra in this taxon is 124 mm long. If the smaller size estimate is correct, Nanshiungosaurus brevispinus' twelfth cervical (topologically equivalent to N? bohlini's first dorsal, as the latter has two less cervicals) is 76 mm long, but if the larger estimate is correct, it is 129 mm long. This would make N. brevispinus equivalent to N? bohlini in size, clearly not what Dong thought was true when describing the latter species. Note both of the reasons involve Dong, who described Nanshiungosaurus and should therefore know its size.
The pelvis is of similar size to Enigmosaurus, Nothronychus and Segnosaurus (IGM 100/80). The width and height of the illustrated twelfth cervical and third dorsal average 85% (76-91%) of the equivalents in Nothronychus' anterior dorsal (which is one of the first three in the series). Subtracting for spaces between centra in the mounted specimen gives a cervical length of 1400 mm, a dorsal length of 730 mm and a sacral length of 680 mm. Adding 440 mm for a Segnosaurus-sized skull and 1200 mm for a Neimongosaurus-proportioned tail gives a total length of 4.45 meters.
References- Dong, 1979. The Cretaceous dinosaur fossils in southern China. In Institute of Vertebrate Paleontology and Paleoanthropology and Nanjing Institute of Paleontology (eds.). Mesozoic and Cenozoic Red Beds in Southern China. Science Press. 342-350.
Paul. 1984. The segnosaurian dinosaurs: Relics of the prosauropod-ornithischian transition? Journal of Vertebrate Paleontology. 4(4), 507-515.
Paul, 1988. Predatory Dinosaurs of the World. Simon & Schuster: New York 464 pp.
Russell, Russell and Sweet, 1993. The end of the dinosaurian era in the Nanxiong Basin. Vertebrata PalAsiatica. 31(2), 139-145.
Russell and Dong, 1994. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences. 30, 2107-2127.
Dong and Yu, 1997. A new segnosaur from Mazongshan Area, Gansu Province, China. in Dong (ed). Sino-Japanese Silk Road Dinosaur Expedition. China Ocean Press, Beijing. 90-95.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. in In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Le Loeuff, 2012. Paleobiogeography and biodiversity of Late Maastrichtian dinosaurs: How many dinosaur species went extinct at the Cretaceous-Tertiary boundary? Bulletin de la Société Géologique de France. 183(6), 547-559.
Ke, Rahman, Song, Hu, Niu, Lou, Li and Han, 2023. A new species of Nanhsiungchelys (Testudines: Cryptodira: Nanhsiungchelyidae) from the Upper Cretaceous of Nanxiong Basin, China. PeerJ. 11:e15439.

"Nanshiungosaurus" bohlini Dong and Yu, 1997
Early Albian, Early Cretaceous
Lower Red Beds of the Zhonggou Formation, Gansu, China
Holotype- (IVPP V 11116; lost) (5.3 m; ~1 ton) atlas, axis (148 mm), third cervical vertebra (146 mm), fourth cervical vertebra (161 mm), fifth cervical vertebra (163 mm), sixth cervical vertebra (164 mm), seventh cervical vertebra (183 mm), eighth cervical vertebra (183 mm), ninth cervical vertebra (184 mm), tenth cervical vertebra (183 mm), eleventh cervical vertebra, cervical ribs, first dorsal vertebra (124 mm), second dorsal vertebra, third dorsal vertebra, fourth dorsal vertebra, fragmentary dorsal ribs
Diagnosis- (after Dong and Yu, 1997) differs from Falcarius, Alxasaurus, Neimongosaurus and Nanshiungosaurus brevispinus in having platycoelous cervical centra; primitively differs from Nanshiungosaurus brevispinus in having transversely narrow anterior dorsal neural spines.
(proposed) primitively differs from Nanshiungosaurus brevispinus and Neimongosaurus in having eleven cervical vertebrae; primitively differs from Beipiaosaurus in having an axial neural spine which rises anteriorly; primitively differs from Falcarius and Erliansaurus in having cervicals without a median keel; differs from Neimongosaurus in that cervical centra 7-10 are longer than 5-6; differs from Beipiaosaurus, Alxasaurus, Nothronychus mckinleyi, Erliansaurus and Neimongosaurus in having fused cervical ribs; differs from Nothronychus? graffami, Erliansaurus and Nanshiungosaurus brevispinus in having amphiplatyan dorsal centra; primitively differs from Erliansaurus in having anterior dorsal pleurocoels.
Other diagnoses- Dong and Yu (1997) included several additional characters in their diagnosis. The large size is matched or exceeded by several other therizinosaurs (Therizinosaurus, Segnosaurus, Suzhousaurus, etc.). They use the platycoelous cervicals and anterior dorsals as a diagnostic character, contrasting them with Nanshiungosaurus brevispinus' opisthocoelous posterior cervicals and platycoelous anterior cervicals and dorsals. The cervical centra are also platycoelous in Nothronychus, Erlikosaurus, Segnosaurus, posterior cervicals of Falcarius, and anterior cervicals of Nanshiungosaurus brevispinus, but amphiplatyan in Alxasaurus, and amphicoelous in Neimongosaurus and posterior cervicals of Falcarius. Which state is derived is difficult to determine, as Caudipteryx has amphicoelous centra, Microvenator has platycoelous centra and the Morrison oviraptoriform has opisthocoelous centra. Low and long cervical neural spines are found in all therizinosaurs. The cervical zygapophyses are not longer or wider than in other taxa such as Neimongosaurus or Falcarius. Dong and Yu state the cervical zygapophyses are placed well above the neural canals, which is true in Falcarius as well, especially in posterior cervicals. It is also true in Neimongosaurus' mid cervicals and Nanshiungosaurus brevispinus' posterior cervicals, while the dorsally exposed neural canal in Nothronychus may be due to damage. The anterior dorsal neural spines are said to be low, which matches Falcarius, Nanshiungosaurus brevispinus, Nothronychus mckinleyi and N? graffami, though those of Alxasaurus and Neimongosaurus are tall. They are also diagnosed as being narrow, which matches Falcarius, though Alxasaurus and the Nothronychus species have spines which taper to narrow apices, and Nanshiungosaurus brevispinus' is broad. Finally, anterior dorsal vertebrae with ventral keels are present in all therizinosaurs.
The number of cervical vertebrae is lower than Nanshiungosaurus brevispinus (12) or Neimongosaurus (14), but may be the same as Beipiaosaurus (11-12) and basal oviraptorosaurs. Fused cervical ribs are present, like Falcarius, Erlikosaurus, Nanshiungosaurus brevispinus and Segnosaurus, but unlike Beipiaosaurus, Alxasaurus, Erliansaurus, Nothronychus mckinleyi and Neimongosaurus.
Comments- Nanshiungosaurus bohlini was discovered in 1992. Dong and Yu (1997) list different lengths for vertebral centra in the text than they do in the measurement table. In the text, the axis is 152 mm, the seventh and eighth cervicals are 192 mm and the ninth and tenth are 143 mm. They also later state the dorsals are platycoelous, instead of amphiplatyan. Zanno (2010) indicates the specimen is lost.
This is a difficult specimen to evaluate, as the description is brief, only the cervicals in dorsal and ventral views were photographed, the specimen is lost, comparative vertebrae in other therizinosaurs are often broken or distorted, and most other therizinosaur vertebrae are from uncertain positions in the presacral column. Consequently, there are no known diagnostic characters for the species, though a combination of primitive characters does distinguish it from most contemporaneous therizinosaurs (Falcarius, Beipiaosaurus, Alxasaurus). However, it cannot be compared with Suzhousaurus from the same stratigraphic group besides agreeing in general anterior dorsal morphology, and may be synonymous. If they are indeed synonymous, Li et al. (2007) note the correct name will be Suzhousaurus bohlini. Forcing it to be sister to Suzhousaurus in Hartman et al.'s (2019) matrix takes 2 additional steps. Dong and Yu gave no reason to refer the species to Nanshiungosaurus, it lived much earlier than that genus, and the number of cervical vertebrae may indicate it is outside the clade formed by Nanshiungosaurus and Neimongosaurus. Li et al. and Zanno agree the species is not Nanshiungosaurus and put the genus in quotes. Forcing Nanshiungosaurus monophyly in Hartman et al.'s matrix only takes a single step. In their analysis, bohlini resolves as a therizinosaurid in the Segnosaurus plus Nothronychus clade, unlike Nanshiungosaurus brevispinus or Suzhousaurus.
References- Dong and Yu, 1997. A new segnosaur from Mazongshan Area, Gansu Province, China. In Dong (ed.). Sino-Japanese Silk Road Dinosaur Expedition. China Ocean Press, Beijing. 90-95.
Tang, Luo, Zhou, You, Georgi, Tang, and Wang, 2001. Biostratigraphy and palaeoenvironment of the dinosaur-bearing sediments in Lower Cretaceous of Mazongshan area, Gansu Province, China. Cretaceous Research. 22(1), 115-129.
Li, Peng, You, Lamanna, Harris, Lacovata and Zhang, 2007. A large therizinosauroid (Dinosauria: Theropoda) from the Early Cretaceous of northwestern China. Acta Geologica Sinica (English Edition). 81(4), 539-549.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
You, Morschhauser, Li and Dodson, 2018. Introducing the Mazongshan dinosaur fauna. Journal of Vertebrate Paleontology. 38(supp. 1), 1-11.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247

Segnosaurus Perle, 1979
S. galbinensis Perle, 1979
Cenomanian-Santonian, Late Cretaceous
Amtgai, Baynshiren Formation, Mongolia
Holotype- (IGM 100/80) (5.3 m; 1 ton) mandibles (~379 mm; one partial), basioccipital, dorsal rib fragments (lost), median gastralium (lost), sacrum, ten proximal caudal vertebrae (lost), fifteen distal caudal vertebrae (lost), incomplete humerus (lost), radius (lost), ulna (lost), phalanx II-1 (99 mm; lost), phalanx II-2 (100 mm; lost), manual ungual II (195 mm; lost), incomplete ilia (750 mm; one lost), pubes (750 mm; one lost), ischia (650 mm; one lost), incomplete femur
Cenomanian-Santonian, Late Cretaceous
Khara Khutul, Baynshiren Formation, Mongolia
Paratypes- (IGM 100/82) (7.0 m; 2.4 tons) dorsal rib fragments (lost), incomplete ilia (one lost), distal pubis (lost), proximal ischium (lost), femur (~1050 mm; only shaft fragment not lost), proximal femur, tibia (860 mm, 260 wide; proximal portion lost), fibula (765 mm; lost), astragalus, calcaneum, distal tarsal III, distal tarsal IV, metatarsal I (145 mm; lost), phalanx I-1 (82 mm; lost), pedal ungual I (lost), metatarsal II (218 mm; lost), phalanx II-1 (88 mm; lost), metatarsal III (274 mm; lost), phalanx III-1 (88 mm; lost), metatarsal IV (266 mm; lost), phalanx IV-1 (51 mm; lost), metatarsal V (96 mm; lost)
(>7 m) posterior ilium
Cenomanian-Santonian, Late Cretaceous
Amtgai, Baynshiren Formation, Mongolia
(IGM 100/83) (6.3 m; 1.8 tons) fragmentary cervical neural arch, scapulocoracoid (lost), humeri (one proximal; 560 mm), radii (335 mm), ulna (390 mm), manual ungual (lost)
Cenomanian-Santonian, Late Cretaceous
Amtgai, Baynshiren Formation, Mongolia
Referred- (IGM 100/81) tibia, fibula, astragalus, calcaneum (Barsbold and Perle, 1980)
Cenomanian-Santonian, Late Cretaceous
Bayshin Tsav, Baynshiren Formation, Mongolia
?(IGM coll.; field #8) fibula (Zanno, 2010)
(IGM coll.; field #93) pubis (Zanno, 2010)
Diagnosis- (after Perle, 1979) dorsoventrally compressed manual phalanges II-1 and II-2.
(after Clark et al., 1994) at least nine pairs of elongate anterior dentary teeth.
(after Clark et al., 2004) twenty-four dentary teeth.
(after Zanno, 2010) coronoid process on surangular; humerus straight in lateral view; deep brevis fossa; pubic foot only very slightly projected posteriorly.
(after Zanno et al., 2016) ratio of edentulous anterior dentary length to tooth row length ~1:5; pronounced ventral deflection of anterior dentary (~30 degrees); dentary tooth row arched, over half dorsoventral height dorsal to transverse axis of dentigerous portion of dentary; minimum dorsoventral height of dentary posterior to tooth row, dentary constricted between posteriormost tooth row and contact with surangular; lateral dentary shelf located midway between dorsal and ventral margins; significant proportion (~1/4th) of dorsal dentary margin edentulous posterior to tooth row, tooth row does not extend to surangular articulation; medial margin of dental alveolus crenulate (scalloped); ventral foramen of splenial located anterior to dorsal foramen; posterior margin of splenial bears a near 90 degree notch to receive prearticular; posterolateral surangular shelf absent; surangular dorsoventrally shallow over external mandibular fenestra; ventral aspect of angular flat; prearticular ventrally displaced, posterior portion contributes to ventral margin of hemimandible in medial view; body of prearticular relatively straight; anteriormost aspect of prearticular terminates in expanded, subcircular tab; mesial carina of tooth crown folded distally and serrated; extracarinal denticles populate mesial face of tooth crown; basal portion of mesial carina bears serrated, triangular facet at cervix; distalmost lateral dentary teeth subconidont, bearing triple carinae.
Other diagnoses- As this was the first recognized "segnosaur", most of Perle's (1979) original diagnostic characters are now known to have a wider distribution. Some are primitive for therizinosaurs- mandible slender; teeth small; anterior dentary teeth recurved; anterior dentary teeth highly labiolingually compressed; posterior dentary teeth lanceolate; bipedal; unreduced forelimbs; well developed deltopectoral crest; manual ungual I highly curved, pointed and transversely compressed; elongate pubic symphysis. Many are now diagnostic of more inclusive therizinosaur clades- closely packed dentary teeth; anterior dentary teeth larger than posterior teeth; posterior dentary teeth slightly recurved; posterior dentary teeth slightly labiolingually compressed; short distal caudal vertebrae; fused scapulocoracoid; ligament pits poorly developed on manual phalanges; ilia widely separated due to elongate sacral ribs and transverse processes; laterally flared preacetabular process; short postacetabular process; lateral tuberosity on postacetabular process; opisthopubic pelvis; transversely flattened ischium; distally placed obturator process; obturator process contacts pubis; astragalar ascending process laterally deflected; calcaneum fits into deep notch on astragalus; calcaneum has mobile articulation with astragalus; metatarsal I contacts tarsus; short metatarsus; metatarsals not compressed proximally. A few are too vague to evaluate- sacral ribs and transverse processes, scapulocoracoid, pelvis and metatarsus massive.
Barsbold and Perle (1980) diagnosed Segnosaurus by its thick pedal unguals, but these are plesiomorphic for therizinosaurs.
Barsbold (1983) lists the small symphyseal diastema in the dentary, but this is plesiomorphic.
Contra Clark et al. (1994), the dentary teeth do not have a high DSDI.
Clark et al. (2004) listed six sacral vertebrae in their diagnosis, but this is also present in Nothronychus? graffami and Nanshiungosaurus.
Of Zanno's (2010) diagnostic characters, an overhanging dorsal ilial margin is present in Nothronychus? graffami (due to crushing?) and possibly Alxasaurus. A deep distodorsal ischial process is also present in Suzhousaurus and probably Nanshiungosaurus. She also lists hypertrophied distal epiphyses of the metatarsals, but there seems to be little difference between Segnosaurus and other therizinosaurs more derived than Falcarius in this regard. A subrectangular obturator process is also present in Suzhousaurus and Nothronychus? graffami. The subcircular puboischial fenestra is also present in Enigmosaurus and Suzhousaurus. A proximodistally deep obturator process is also present in Nothronychus mckinleyi and probably N? graffami. The absence of medial fusion of the obturator processes is plesiomorphic, while the absence of a fused pubic symphysis may be ontogenetic. An anteroposteriorly wide distal pubic shaft is also present in Suzhousaurus and Nothronychus? graffami. The brevis fossa may not be deeper than that of Neimongosaurus, which is described as having a "moderately developed" brevis shelf.
Comments- The remains of Segnosaurus were discovered in 1973-1975, and were first noted by Barsbold (1976) who mentioned "A large, laterally compressed ungual phalanx, similar in structure and form to that attributed to Alectrosaurus, belongs to another previously unknown dinosaur (under study) found there [Baynshiren Formation]. This dinosaur does not belong to Tyrannosauridae." Barsbold (1979) illustrated and briefly described the pelvis as "segnosaurid", as the official description was still in press. The holotype of Segnosaurus galbinensis (IGM 100/80; mistyped 100/90 by Barsbold, 1983) includes a mandible, pelvis and forelimb and vertebral elements. Unfortunately, only the mandibular, manual and pelvic dimensions are described. Naish (online, 2007) noted a basioccipital is also present, as was shown to him by Perle, though never mentioned in the literature. Barsbold (1983) also lists carpal remains for the holotype. Zanno (2010) notes the vertebral, forelimb and hindlimb material is lost, and the pelvis is damaged. Zanno also photographs the holotype pelvis, which differs from earlier illustrations in several respects- the anterodorsal ilial margin is more rounded, the ischial peduncle of the ilium larger, the postacetabular process is rectangular and projects ventrally, the pubis is extremely concave anteriorly and expands gradually toward the boot, the distodorsal ischial process is larger, the distal ischial end is longer and narrower, and the obturator process is much larger. The pelvis is of virtually identical size to Nothronychus, suggesting this specimen was also close to 5.3 meters. A referred specimen (IGM 100/83) is a cervical neural arch, pectoral girdle and forelimb, the latter missing all manual material save an ungual. Zanno notes that the pectoral girdle and manual ungual are lost. The forelimb elements are about 20% larger than Nothronychus', so the specimen may have been about 6.3 meters long. Another possibility is that this was similar in size to the holotype, but Segnosaurus has proportionately longer arms than Nothronychus. The holotype includes comparable elements (humerus, radius, ulna), so the problem is soluble granted someone examines the remains. The second referred specimen (IGM 100/82) includes rib fragments, partial pelvis and virtually complete hindlimb. Zanno notes the ribs, most of the pelvic material, and some of the hindlimb material including the pes are lost. He also finds a posterior ilium which is not referrable to this individual catalogued under the same number. There is confusion regarding the limb element length in this specimen. Barsbold and Perle (1980) state the tibia is shorter than the femur, but cite a femoral length of 840 mm and a tibial length of 860 mm. Barsbold and Maryanska (1990) stated the tibia was "more than 80%" of femoral length. The illustration in Barsbold and Perle suggests the tibia is about 830 mm long. This is very close to the cited measurement, suggesting the latter is accurate. The femur would then be slightly less than 1075 mm in length. Comparing the hindlimb elements to other segnosaurs indicates it was approximately 7.0 meters long. Again, it's possible this was similar in size to the type, but had proportionately longer hindlimbs than Nothronychus. And again, examination of the partial pelvis the two share in common could resolve the problem. Barsbold (1983) lists IGM 100/87 and 100/88 as referred specimens, but these are probably typos for 100/82 and 100/83.
Currie and Eberth (1993) suggested isolated elements recovered by the Sino-Canadian expeditions in 1988 and 1990 from the Iren Dabasu Formation (Late Campanian-Early Maastrichtian) are indistinguishable from Segnosaurus, but given their provenence it is more likely these are Erliansaurus, Neimongosaurus and/or the taxon represented by AMNH 6368.
References- Barsbold, 1976. New data on Therizinosaurus (Therizinosauridae, Theropoda). In Kramarenko, Luvsandansan, Voronin, Barsbold, Rozhdestvensky, Trofimov and Reshetov (Eds.). Paleontology and Biostratigraphy of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition, Transactions. 3, 76-92.
Barsbold, 1979. Opisthopubic pelvis in the carnivorous dinosaurs. Nature. 279, 792-793.
Perle, 1979. Segnosauridae - A new family of theropods from the Late Cretaceous of Mongolia. Trudy - Sovmestnaya Sovetsko-Mongol'skaya Paleontologicheskaya Ekspeditsiya. 8, 45-55.
Barsbold and Perle, 1980. Segnosauria, a new infraorder of carnivorous dinosaurs. Acta Palaeontologica Polonica. 25, 185-195.
Barsbold, 1983. Carnivorous dinosaurs from the Cretaceous of Mongolia. Transactions of the Joint Soviet-Mongolian Palaeontological Expedition. 19, 117 pp.
Barsbold and Maryanska, 1990. Saurischia sedis mutabilis: Segnosauria. in Weishampel, Dodson and Osmolska (eds). The Dinosauria. University of California Press. 408-415.
Currie and Eberth, 1993. Palaeontology, sedimentology and palaeoecology of the Iren Dabasu Formation (Upper Cretaceous), Inner Mongolia, People's Republic of China. Cretaceous Research. 14, 127-144.
Clark, Maryanska and Barsbold, 2004. Therizinosauroidea. in In Weishampel, Dodson and Osmolska (eds). The Dinosauria Second Edition. University of California Press. 151-164.
Naish, online 2007. https://web.archive.org/web/20090212202320/https://scienceblogs.com/tetrapodzoology/2007/02/therizinosauroids_and_altanger.php
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Zanno, Tsogtbaatar, Chinzorig and Gates, 2016. Specializations of the mandibular anatomy and dentition of Segnosaurus galbinensis (Theropoda: Therizinosauria). PeerJ. 4:e1885.

unnamed therizinosaurid (Gilmore, 1933)
Middle-Late Campanian, Late Cretaceous
AMNH 138, Iren Dabasu Formation, Inner Mongolia, China
Material- (AMNH 6368; syntype of Alectrosaurus olseni) humerus (390 mm), manual ungual I (190 mm on curve), manual phalanx II-1 (74 mm)
?... (AMNH 21784) three mid caudal vertebrae (~41, ~38, ~35 mm), distal caudal centrum (~24 mm) (Mader and Bradley, 1989)
?... (uncollected) two or three elements (Mader and Bradley, 1989)
Comments- AMNH 6368 was found on May 4 1923 at Third Asiatic Expedition field site 138, 30 meters away from the lectotype of Alectrosaurus olseni and was thought to belong to the same individual in the field. Gilmore (1933) prefered to treat them as two individuals. He placed them in the same species due to the similarity between the manual unguals, which are “laterally compressed, strongly curved and have sharply curved extremities”, as well as the association in the field and slenderness. Gilmore originally diagnosed A. olseni partially on the characteristics of this specimen. Rozhdestvensky (1970) recognized the similarity to Therizinosaurus and referred Alectrosaurus to Therizinosauridae, but Barsbold (1976) and Perle (1977) correctly removed the forelimb from that taxon based on supposed Alectrosaurus specimen IGM 100/50 with small humerus and manual ungual. Mader and Bradley (1989) described the specimen in detail as a segnosaurid. Zanno (2010) notes the slender proportions, poorly defined medial tuberosity, and posterior humeral trochanter indicates it is not referable to Neimongosaurus, and it is more gracile than Erliansaurus and lacks that genus' distinctive crest-shaped posterior trochanter. Zanno (2006) recovered it as more derived than Alxasaurus in her phylogenetic analysis, and most recently Hartman et al. (2019) found it sister to Segnosaurus in Therizinosauridae.
AMNH 21784 was also discovered on May 4 1923 at Third Asiatic Expedition field site 138, but not catalogued until 1984 and not described until 1989 by Mader and Bradley. While those authors described them as Theropoda incertae sedis, they may be therizinosauroid based on their resemblence to Alxasaurus' mid caudals (e.g. short centra that become shorter distally; low neural spines; similarly placed transverse processes) although their neural spines are more posteriorly restricted and their prezygapophyses are longer. Although Mader and Bradley considered the caudals too small to belong to the same individual as the humerus, they were comparing them to theropod proximal caudals as they were unaware of therizinosauroids' modified caudal series with relatively homogenous caudals decreasing in length distally. In fact, given that Alxasaurus' holotype humerus is 4% longer than AMNH 6368, its fourteenth-eighteenth caudals are also slightly longer (39-44 mm) as is an isolated distal caudal (26 mm), so the sizes are appropriate to belong to a single therizinosauroid individual. As they are from the same field site, that is provisionally accepted here. Mader and Bradley also noted "two or three unspecified [theropod] elements that regrettably were not collected due to their "poor condition" (Granger's field record, Third Asiatic Expedition)" found with the forelimb and caudal material and might also belong to the same individual.
References- Gilmore, 1933. On the Dinosaurian Fauna of the Iren Dabasu Formation. Bulletin American Museum of Natural History. 67, 23-78.
Rozhdestvensky, 1970. Giant claws of enigmatic Mesozoic reptiles. Paleontological Journal. 1970(1), 131-141.
Barsbold, 1976. New data on Therizinosaurus (Therizinosauridae, Theropoda). In Kramarenko, Luvsandansan, Voronin, Barsbold, Rozhdestvensky, Trofimov and Reshetov (Eds.). Paleontology and Biostratigraphy of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition, Transactions. 3, 76-92.
Perle, 1977. On the first discovery of Alectrosaurus (Tyrannosauridae, Theropoda) from the Late Cretaceous of Mongolia. Problemy Geologii Mongolii. 3, 104-113.
Mader and Bradley, 1989. A redescription and revised diagnosis of the syntypes of the Mongolian tyrannosaur Alectrosaurus olseni. Journal of Vertebrate Paleontology. 9(1), 41-55.
Zanno, 2006. The pectoral girle and forelimb of the primitive therizinosauroid Falcarius utahensis (Theropoda, Maniraptora): Analyzing evolutionary trends within Therizinosauroidea. Journal of Vertebrate Paleontology. 26(3), 636-650.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247.

Erlikosaurus Perle in Barsbold and Perle, 1980
= Erlicosaurus Perle, 1981
E. andrewsi Perle in Barsbold and Perle, 1980
= Erlicosaurus andrewsi Perle, 1981
Cenomanian-Santonian, Late Cretaceous
Bayshin Tsav, Baynshiren Formation, Mongolia
Holotype- (IGM 100/111) (~3.4 m; ~275 kg) incomplete skull (237 mm, 258 to the occipital condyle), mandibles (246 mm), several fragmentary cervical vertebrae, humerus (300 mm), metatarsal I (71 mm), phalanx I-1 (42 mm), pedal ungual I (100 mm), metatarsal II (120 mm), phalanx II-1 (44 mm), phalanx II-2 (42 mm), pedal ungual II (89 mm), distal metatarsal III (~122 mm), phalanx III-1 (40 mm), phalanx III-2 (36 mm), phalanx III-3 (35 mm), pedal ungual III (84 mm), distal metatarsal IV, phalanx IV-1 (38 mm), phalanx IV-2 (15 mm), phalanx IV-3 (15 mm), phalanx IV-4 (27 mm), pedal ungual IV (73 mm)
Diagnosis- (after Barsbold and Perle, 1980) lateral pedal unguals narrow.
(after Perle, 1981) twenty-three maxillary teeth (unknown in other therizinosaurs); dentary symphysis more medially recurved than Segnosaurus, Neimongosaurus or Falcarius; dentary teeth not at all recurved (also in CAGS-01-IG-1); distal condyles of humerus sharply separated proximally from shaft (also in Neimongosaurus); .
(after Clark et al., 1994) premaxillary fenestra absent (unknown in other therizinosaurs); maxillary fenestra absent; maxillary teeth inset from lateral margin (unknown in other therizinosaurs); vomer extremely elongate and extending posteriorly to meet cultriform process (also in an undescribed Chinese therizinosaur- Zanno, 2010); passage for internal carotid artery enclosed on occiput; external auditory meatus restricted ventrally by lateral expansion of braincase (unknown in other therizinosaurs); trigeminal opening divides into three branches within side wall of braincase (unknown in other therizinosaurs); lateral dentary shelf begins at fifth tooth position.
(after Zanno et al., 2016) ratio of edentulous anterior dentary length to tooth row length ~1:8; slight ventral deflection of anterior dentary (~4 degrees); lateral dentary shelf extensive, reaches posterior termination of tooth row; lateral dentary shelf sharp, distinctly raised from lateral surface; tooth row extends to surangular articulation; posterodorsal dentary process visible in lateral view; ventral splenial foramen located posterior to dorsal foramen; posterolateral surangular shelf present; lateral body of surangular dorsoventrally deep; prearticular bears dorsal tab.
Other diagnoses- Contra Zanno (2010), the transversely compressed pedal unguals noted by Barsbold and Perle (1980) are diagnostic, as they differ from Alxasaurus, "Chilantaisaurus" zheziangensis, Nothronychus? graffami and Segnosaurus. Nothronychus mckinleyi has narrow medial pedal unguals (originally identified as manual unguals), but thick lateral unguals, unlike Erlikosaurus.
Perle (1981) included several characters in his diagnosis which distinguish Erlikosaurus from Segnosaurus, the only other recognized therizinosaur at the time. The sharp raised alveolar edge on the dentary symphysis and extensive length of this toothless area are also present in Neimongosaurus. While Perle lists the maxillary tooth count as being 24(25?), it is really 23, which is only diagnostic due to the unknown counts in other therizinosaurs. The 31 dentary teeth are not significantly more numerous than the 28 teeth in Falcarius. The lack of a coronoid prominence on the surangular is primitive. The metatarsal II / humeral ratios of Erlikosaurus and Segnosaurus are not significantly different- 36% vs. 38%.
Barsbold (1983) listed small, closely positioned teeth in his diagnosis, but these are present in all therizinosaurs. The toothless dentary symphysis is present in other derived therizinosaurids as well (e.g. Neimongosaurus; Segnosaurus).
Barsbold and Maryanska (1990) listed the less flattened anterior dentary teeth compared to Segnosaurus, but this is plesiomorphic.
Relatively few therizinosaurs can be evaluated for the characters listed by Clark et al. (1994) in their diagnosis, as cranial remains are rare and the complete skull of Beipiaosaurus is still undescribed. A toothless premaxilla with sharp ventral edges is also present in the Nanchao therizinosaur embryo (CAGS-01-IG-1). The elongate external nares are also present in Beipiaosaurus and the Nanchao embryo. The sharp ventral edge of the antorbital fossa is also observed in Falcarius. The antorbital fossa is equally extensive in Beipiaosaurus, though not in the Nanchao embryo (perhaps due to ontogenetic shortening of the snout). Both Beipiaosaurus and the Nanchao embryo have a maxillary fenestra, unlike Erlikosaurus, though other therizinosaurs cannot be evaluated. A reduced number of nutrient foramina are present on the posterior maxilla in both Falcarius and the Nanchao embryo. The posterodorsal jugal process also extends dorsally up the laterotemporal fenestra margin in the Nanchao embryo. The basisphenoid also has extremely large peumatic spaces in the Nanchao embryo and Nothronychus mckinleyi. The anterior carotid foramen does not seem to be exposed on the occiput of Falcarius, Nothronychus mckinleyi or the Nanchao embryo, though it is unknown in other therizinosaurs. A generally homodont dentition of linguolabially flattened teeth is primitive for theropods, while maxillary teeth which are small, lanceolate, unrecurved and constricted at the base are present in Falcarius and likely all therizinosaurs, as maxillary and dentary dentition is usually extremely similar. Likewise, coarsely serrated maxillary teeth are not currently known for any other therizinosaur (Falcarius has plesiomorphically small serrations), but are likely present in all derived therizinosaurs, as their dentary teeth are coarsely serrated. Clark et al. note that Erlikosaurus has fewer elongate anterior teeth than Segnosaurus, but this is probably primitive, as Falcarius is similar in this regard. The other mandibular characters listed in their diagnosis are specified either as being shared with other therizinosauroids, or as being shared with either Alxasaurus or Segnosaurus.
Comments- Discovered in 1972, Erlikosaurus was confusingly described as gen. et sp. nov. in both Barsbold and Perle (1980) and Perle (1981), though the former attributes the name to Perle only. Perle (1981) spelled the genus name Erlicosaurus, which has been followed by some authors (e.g. Barsbold, 1983; Clark et al., 1994). However, according to the ICZN (Article 32.5), since there is no evidence in the original publication that the name is spelled incorrectly, and the issue is not with suffix or gender, Erlikosaurus is the correct original spelling. This makes Erlicosaurus an unjustified emendation (Article 33.2), since there is no evidence in Perle (1981) that he purposefully changed the spelling, and the original spelling is not cited. According to Article 33.2.3, "the name thus emended is available and it has its own author and date and is a junior objective synonym of the name in its original spelling." An unjustified emendation can become justified it it has prevailing usage and is attributed the the original author and date, but Erlikosaurus has 33,500 Google hits vs. 1,410 for Erlicosaurus, and 254 vs. 106 Google Scholar hits (as of 8-21-2019). Thus the genus should be spelled Erlikosaurus. Barsbold and Perle (1980) note a left and right pes, but only a single pes is described by Perle (1981).
Currie and Eberth (1993) suggested isolated elements recovered by the Sino-Canadian expeditions in 1988 and 1990 from the Iren Dabasu Formation (Late Campanian-Early Maastrichtian) are indistinguishable from Erlikosaurus, but given their provenence it is more likely these are Erliansaurus, Neimongosaurus and/or the taxon represented by AMNH 6368. Frontal CMN 12355 from the Dinosaur Park Formation has been referred to Erlikosaurus (Currie, 1987), but has since been recognized as troodontid (see discussion under Therizinosauria).
Erlikosaurus andrewsi is known from a skull, fragmentary cervical vertebrae, humerus and pes. Unfortunately, the vertebral dimensions are undescribed, so the length can be only loosely estimated. Based on the humeral, cranial and metatarsal lengths, Erlikosaurus was somewhere around 3.4 meters long.
References- Barsbold and Perle, 1980. Segnosauria, a new infraorder of carnivorous dinosaurs. Acta Palaeontologica Polonica. 25, 185-195.
Perle, 1981. A new segnosaurid from Mongolia. Trudy - Sovmestnaya Sovetsko-Mongol'skaya Paleontologicheskaya Ekspeditsiya. 15, 50-59. [in Russian]
Barsbold, 1983. Carnivorous dinosaurs from the Cretaceous of Mongolia. Transactions of the Joint Soviet-Mongolian Palaeontological Expedition. 19, 117 pp.
Currie, 1987. Theropods of the Judith River Formation of Dinosaur Frovincial Park, Alberta. In Currie and Koster (eds). 4th Symposium of Mesozoic Terrestrial Ecosystems Short Papers. Tyrell Museum of Palaeontology, Drumheller, Alberta. 52-60.
Barsbold and Maryanska, 1990. Saurischia sedis mutabilis: Segnosauria. in Weishampel, Dodson and Osmolska (eds). The Dinosauria. University of California Press. 408-415.
Currie and Eberth, 1993. Palaeontology, sedimentology and palaeoecology of the Iren Dabasu Formation (Upper Cretaceous), Inner Mongolia, People’s Republic of China. Cretaceous Research. 14, 127-144.
Clark, Perle and Norell, 1994. The skull of Erlicosaurus andrewsi, a Late Cretaceous "segnosaur" (Theropoda: Therizinosauridae) from Mongolia. American Museum Novitates. 3115, 39 pp.
Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.
Lautenschlager, Rayfield, Witmer and Perle, 2011. The endocranial anatomy of the Mongolian therizinosauroid dinosaur Erlikosaurus andrewsi as revealed by 3D visualization. Journal of Vertebrate Paleontology. Program and Abstracts 2011, 141.
Lautenschlager, Rayfield, Witmer and Perle, 2012. A biomechanical model of Erlikosaurus andrewsi (Dinosauria: Therizinosauria) with implications for cranial function and dietary preferences. Journal of Vertebrate Paleontology. Program and Abstracts 2012, 126.
Lautenschlager, Rayfield, Perle, Zanno and Witmer, 2012. The endocranial anatomy of Therizinosauria and its implications for sensory and cognitive function. PLoS ONE. 7(12), e52289.
Lautenschlager, 2013a. Unravleing therizinosaur paleobiology - a multi-angle approach. Journal of Vertebrate Paleontology. Program and Abstracts 2013, 160.
Lautenschlager, 2013b. Cranial myology and bite force performance of Erlikosaurus andrewsi: A novel approach for digital muscle reconstructions. Journal of Anatomy. 222(2), 260-272.
Zanno, Tsogtbaatar, Chinzorig and Gates, 2016. Specializations of the mandibular anatomy and dentition of Segnosaurus galbinensis (Theropoda: Therizinosauria). PeerJ. 4:e1885.

Nothronychus Kirkland and Wolfe, 2001
Other diagnoses- Contra Zanno et al. (2009), graffami does not share many unique characters with Nothronychus mckinleyi. Notably, the obturator process of Nothronychus graffami is not necessarily more subcircular than that of Segnosaurus and Nanshiungosaurus. The puboischial fenestra's elongation cannot be measured in N. mckinleyi due to the missing pubes and seems equally elongate in Nanshiungosaurus in any case. The pubic contact on the obturator process is also limited to its distal portion in Suzhousaurus and probably Enigmosaurus and Nanshiungosaurus. The deep post-obturator notch on the ischium is also present in Suzhousaurus. This limits their shared characters to just the distally tapering scapula, which is only known to be absent in Segnosaurus and Suzhousaurus among therizinosaurids. Only the distally tapering scapula is uniquely shared. As both species share derived characters with other therizinosaurid genera (Suzhousaurus, Segnosaurus, etc.), graffami may deserve its own genus. Hartman et al. (2019) recovered the Nothronychus species in a trichtomy with Erlikosaurus, which could group with either Nothronychus species in the same amount of steps. Yet forcing Nothronychus monophyly only took a single step, and Erlikosaurus itself had an stable position so could move to be sister to e.g. Therizinosaurus in one step as well.
References- Kirkland and Wolfe, 2001. First definitive therizinosaurid (Dinosauria; Theropoda) from North America. Journal of Vertebrate Paleontology. 21(3), 410-414.
Zanno, Gillette, Albright and Titus, 2009. A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution. Proceedings of the Royal Society B. 76(1672), 3505-3511.
Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247. DOI: 10.7717/peerj.7247
N. mckinleyi Kirkland and Wolf, 2001
Mid Turonian, Late Cretaceous
Moreno Hill Formation, New Mexico, US
Holotype- (MSM P2117) braincase, two ?cranial fragments, two ?dentary teeth (8.4 mm), seven cervical vertebrae (125.5, 133.5, 187, 188 mm), cervical rib, second or third dorsal vertebra (84.8 mm), dorsal centrum, dorsal ribs, two gastralia, ~tenth caudal vertebra (66.7 mm), chevron fragment, incomplete scapula (518 mm), humeri (one distal; 415 mm), ulna (304 mm), phalanx I-1, distal metacarpal II, phalanx II-1, ischia (530 mm), tibiae (610, 612 mm), fibula, phalanx I-1 (67.7 mm), pedal ungual I (138 mm), distal metatarsal II, pedal ungual II (124 mm), pedal ungual III (99 mm), phalanx IV-2 (39.2 mm), phalanx IV-4 (8.17 mm), pedal ungual IV (92 mm)
....(MSM P4487) incomplete radius or ulna
Diagnosis- (after Kirkland and Wolfe, 2001) serrations on teeth extend basally to constriction (unknown in N. graffami; also in Alxasaurus); laterally facing scapular glenoid (also in Segnosaurus).
(after Kirkland et al., 2005) braincase narrow (unknown in N. graffami).
(after Zanno et al., 2009) heel on posteroventral surface of caudal centra hypertrophied (approximately one third the dorsoventral length of the caudal centrum); post-obturator notch narrow (also in Suzhousaurus).
Other diagnoses- Kirkland and Wolfe (2001) included several characters in their diagnosis, which Zanno et al. (2009) note are invalid. The coarse serrations and circular root of the tooth are typical for therizinosaurs. Anterior dorsals with "long pedicle and large pleurocoel encasing multiple separate pneumatic foramina" are present in Nanshiungosaurus? bohlini. The slender scapula is shared with N. graffami, so is listed in the Nothronychus diagnosis. The humeral characters (straight, slender shaft; short deltopectoral crest; humeral trochanter absent) are all plesiomorphic. The manual ungual characters (flexor tubercle not extending below the proximal articulation; proximodorsal lip absent) are based on misidentified pedal unguals. The "thin ischium nearly excluded from acetabulum with large, rectangular, medially situated, obturator process" is present in other therizinosauroids such as Segnosaurus and Suzhousaurus. The distally placed m. iliofibularis tubercle on the fibula is shared with other derived therizinosauroids. While the lateral pedal unguals are indeed thick, this is plesiomorphic for therizinosaurs.
Kirkland et al. (2005) listed the almost horizontally oriented supraoccipital in their diagnosis, but this is shared by Falcarius, so may be plesiomorphic. They also revised the pedal ungual thickness character to indicate pedal unguals II-IV are thin and straight, while I is thicker. The pedal unguals are not straight, however. Furthermore, pedal unguals I and II are largest in Erlikosaurus, so the large thin unguals previously identified as manual unguals would be more likely to be unguals I and II in Nothronychus. This leaves the smaller, thicker unguals two be from digits III and IV, reversing Kirkland et al.'s character.
Zanno et al. (2009) also listed platycoelous proximal caudal centra in their diagnosis, as it does differ from the amphicoelous condition in N. graffami. Yet Suzhousaurus and Segnosaurus also share this character. The elongate mid dorsal ischial process which extends opposite to the obturator process and scapular glenoid lacking a buttress are plesiomorphic, shared with most derived therizinosauroids.
Comments- The ischium was originally identified as a Zuniceratops squamosal (as MSM P2106; Wolfe and Kirkland, 1998). Kirkland et al. (2005) described the braincase, and reidentified the manual unguals as pedal unguals based on comparisons to the then undescribed N? graffami, which was confirmed by Zanno et al. (2009). Zanno et al. also recognized additional elements not noted by Kirkland and Wolfe- three cervical vertebrae, a dorsal centrum, a chevron fragment, and pedal phalanx I-1. They also reidentified pedal phalanges IV-3 and IV-4 as III-3 and IV-2, and a supposed ulna as an indeterminate radial or ulnar shaft. Hedrick et al. (2015) added a distal humerus, and reidentified metatarsal I as II, and pedal phalanx III-3 as IV-4. Contra Hedrick et al.'s text, both ulnae are not preserved.
References- Wolfe and Kirkland. 1998. Zuniceratops christopheri n. gen. & n. sp., a ceratopsian dinosaur from the Moreno Hill Formation (Cretaceous, Turonian) of west-central New Mexico. In Lucas, Kirkland, and Estep (eds.). Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin. 14, 307-317.
Kirkland and Wolfe, 2001. First definitive therizinosaurid (Dinosauria; Theropoda) from North America. Journal of Vertebrate Paleontology. 21(3), 410-414.
Kirkland and Wolfe, 2001. A therizinosaurid (Dinosauria: Theropoda) braincase from the Middle Turonian (Cretaceous) of North America. Journal of Vertebrate Paleontology. 21(3), 68A.
Smith, Kirkland, Sanders, Zanno and DeBlieux, 2004. A comparison of North American therizinosaur (Theropoda: Dinosauria) braincases. Journal of Vertebrate Paleontology. 24(3), 180A.
Kirkland, Smith and Wolfe, 2005. Holotype braincase of Nothronychus mckinleyi Kirkland and Wolfe 2001 (Theropoda; Therizinosauridae) from the Upper Cretaceous (Turonian) of West-Central New Mexico. in Carpenter (ed.). The Carnivorous Dinosaurs. 87-96.
Zanno, Gillette, Albright and Titus, 2009. A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution. Proceedings of the Royal Society B. 76(1672), 3505-3511.
Lautenschlager, Rayfield, Perle, Zanno and Witmer, 2012. The endocranial anatomy of Therizinosauria and its implications for sensory and cognitive function. PLoS ONE. 7(12), e52289.
Smith, 2013. Reconstruction of the braincase and associated soft tissues of the North American therizinosaur Nothronychus mckinleyi. Journal of Vertebrate Paleontology. Program and Abstracts 2013, 213.
Smith, 2014. The braincase of the North American therizinosaurian Nothronychus mckinleyi (Dinosauria, Theropoda). Journal of Vertebrate Paleontology. 34(3), 635-646.
Hedrick, Zanno, Wolfe and Dodson, 2015. The slothful claw: Osteology and taphonomy of Nothronychus mckinleyi and N. graffami (Dinosauria: Theropoda) and anatomical considerations for derived therizinosaurids. PLoS ONE. 10(6), e0129449.
Smith, 2015. Craniocervical myology and functional morphology of the small-headed therizinosaurian theropods Falcarius utahensis and Nothronychus mckinleyi. PLoS ONE. 10(2), e0117281.
Smith, Wolfe and Sanders, 2015. Additional braincase material from the North American therizinosaur Nothronychus mckinleyi (Turonian: Moreno Hill Formation, west-central New Mexico). Journal of Vertebrate Paleontology. Program and Abstracts 2015, 214.
N? graffami Zanno, Gillette, Albright and Titus, 2009
= Nothronychus "graffami" Zanno, 2008
Early Turonian, Late Cretaceous
Tropic Shale, Utah, US
Holotype- (UMNH VP 16420) (adult) two cervical vertebrae, first dorsal vertebra (~65 mm), fourth dorsal centrum, fifth dorsal centrum, incomplete sixth dorsal vertebra (~90 mm), seventh dorsal vertebra (~91 mm), incomplete eighth dorsal vertebra (~95.6 mm), ninth dorsal centrum, incomplete tenth dorsal vertebra (~55 mm), eleventh dorsal vertebra (~53 mm), at least fourteen dorsal ribs, gastralia, synsacrum (525 mm), first caudal vertebra (73 mm), second caudal vertebra (57 mm), third caudal vertebra (55 mm), fourth caudal vertebra (70 mm), fifth caudal vertebra (80 mm), sixth caudal vertebra (68 mm), seventh caudal vertebra (72 mm), eighth caudal vertebra (70 mm), ninth caudal vertebra (67 mm), tenth caudal vertebra (72 mm), eleventh caudal vertebra (70 mm), twelfth caudal vertebra (60 mm), thirteenth caudal vertebra (60 mm), fourteenth caudal vertebra (60 mm), fifteenth caudal vertebra (55 mm), sixteenth caudal vertebra (50 mm), seventeenth caudal vertebra (50 mm), eighteenth caudal vertebra (35 mm), nineteenth caudal vertebra (33 mm), twentieth caudal vertebra (34 mm), twenty-first caudal vertebra (28 mm), twenty-second caudal vertebra (21 mm), twenty-third caudal vertebra (24 mm), eight chevrons (~75, 95, 85, ~90, ~63, 55 mm), incomplete scapulocoracoid (~540 mm + ~165 mm), incomplete scapula (~570 mm), incomplete coracoid (~175 mm), humeri (424, 415 mm), radii (274, 275 mm), ulnae (309, 303 mm), metacarpal I (90.5 mm), phalanges I-1 (134 mm), manual ungual I (182 mm straight, 215 mm on curve), metacarpal II (141.2 mm), phalanges II-1 (102 mm), phalanx II-2 (133.4 mm), manual unguals II (187 mm straight, 220 mm on curve, ~198 mm straight, ~270 mm on curve), metacarpals III (121, 126 mm), manual ungual III (177 mm straight, 210 mm on curve), ilia (one incomplete), pubes (one incomplete; 587, 575 mm), incomplete ischia (536, 548 mm), femora (696, 656 mm), tibiae (~654, 644 mm), incomplete fibulae (522 mm), incomplete astragali (171, 173 mm transversely), metatarsal I (133 mm), phalanx I-1 (86.7 mm), metatarsals II (182, 187 mm), phalanx II-1 (78.9 mm), phalanx II-2 (74 mm), pedal ungual II, metatarsals III (215, 217 mm), phalanx III-1 (75.5 mm), incomplete phalanx III-3 (70 mm), metatarsal IV (232 mm), phalanx IV-1 (54 mm), phalanx IV-2 (45 mm), phalanx IV-3 (43 mm), phalanx IV-4 (35.6 mm), pedal phalanx, metatarsal V (74 mm)
Diagnosis- (after Zanno et al., 2009) scapular glenoid with pronounced buttress; pubic boot with small posterior process (unknown in N. mckinleyi); posteroventral margin of pubic boot concave (unknown in N. mckinleyi); mid dorsal process of ischium proximodistally short (less than 5% of the total length of ischium); mid dorsal process of ischium located proximal to obturator foramen.
Other diagnoses- Zanno et al. also listed amphicoelous proximal caudal centra in their diagnosis, as it does differ from the platycoelous condition in N. mckinleyi. Yet Neimongosaurus, Erliansaurus and Nanshiungosaurus share this character. The wide post-obturator notch on the ischium is possibly plesiomorphic, being seen in Segnosaurus and probably Enigmosaurus and is plausibly derived from the absent notch found in most coelurosaurs. The caudal centra lack a strong posteroventral heel unlike N. mckinleyi, but most other therizinosaurs lack this as well. The straight ulna is probably taphonomic (Hedrick et al., 2015).
Comments- This specimen was discovered in 2000 and first identified as therizinosaurid (Gillette et al., 2001), then more specifically as a species of Nothronychus (Gillette et al., 2005). Zanno (2008) referred to it as Nothronychus sp. A, but (accidentally?) labeled it Nothronychus graffami in figure 31 of her unpublished thesis, though this was a nomen nudum at the time since theses don't count according to the ICZN. Zanno et al. (2009) later described and officially named the species. As noted above under the Nothronychus comments, it may not be referrable to that genus.
Hedrick et al. (2015) reidentified the supposed furcula as a gastralium, though mistyped it as referring to N. mckinleyi's description. Contra Hedrick et al.'s text, right metatarsals II and III are preserved, not II and IV.
References- Gillette, 2001. A Late Cretaceous (Early Turonian) therizinosaurid dinosaur (Therizinosauridae, Theropoda) from the Tropic Shale of Southern Utah, USA. NAPC 2001 abstracts.
Gillette, Albright, Titus and Graffam, 2001. Discovery and paleogeographic implications of a therizinosaurid dinosaur from the Turonian (Late Cretaceous) of Southern Utah. Journal of Vertebrate Paleontology. 21(3), 54A.
Gillette, Titus, Albright and Zanno, 2005. Osteology of Nothronychus sp., a Late Cretaceous (Lower Turonian) therizinosaurid dinosaur from Southern Utah. Journal of Vertebrate Paleontology. 25(3), 63A.
McCormick, Horton, Johnson and Gillette, 2006. Depositional environment and taphonomy of a therizinosaurid (Dinosauria) from the Tropic Shale (Cenomanian-Turonian), Kane County, Utah. Journal of Vertebrate Paleontology. 26(3), 98A.
Zanno, 2008. A taxonomic and phylogenetic reevaluation of Therizinosauria (Dinosauria: Theropoda): Implications for the evolution of Maniraptora. PhD Thesis. The University of Utah. 329 pp.
Zanno, Gillette, Albright and Titus, 2009. A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution. Proceedings of the Royal Society B. 76(1672), 3505-3511.
Hedrick, Zanno, Wolfe and Dodson, 2015. The slothful claw: Osteology and taphonomy of Nothronychus mckinleyi and N. graffami (Dinosauria: Theropoda) and anatomical considerations for derived therizinosaurids. PLoS ONE. 10(6), e0129449.