Skip to main content
SpringerLink
Log in

A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah

  • Letter
  • Published:

From Nature

View current issue Submit your manuscript

Abstract

Therizinosauroids are an enigmatic group of dinosaurs known mostly from the Cretaceous period of Asia, whose derived members are characterized by elongate necks, laterally expanded pelves, small, leaf-shaped teeth, edentulous rostra and mandibular symphyses that probably bore keratinized beaks1,2. Although more than a dozen therizinosauroid taxa are known, their relationships within Dinosauria have remained controversial because of fragmentary remains and an unusual suite of characters. The recently discovered ‘feathered’ therizinosauroid Beipiaosaurus from the Early Cretaceous of China helped to clarify the theropod affinities of the group3. However, Beipiaosaurus is also poorly represented. Here we describe a new, primitive therizinosauroid from an extensive paucispecific bonebed at the base of the Cedar Mountain Formation (Early Cretaceous) of east-central Utah4,5. This new taxon represents the most complete and most basal therizinosauroid yet discovered. Phylogenetic analysis of coelurosaurian theropods incorporating this taxon places it at the base of the clade Therizinosauroiden, indicating that this species documents the earliest known stage in the poorly understood transition from carnivory to herbivory within Therizinosauroidea. The taxon provides the first documentation, to our knowledge, of therizinosauroids in North America during the Early Cretaceous.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Figure 1: Skeletal elements of Falcarius utahensis.
Figure 2: Jaws and teeth of Falcarius utahensis.
Figure 3: Phylogenetic relationships of Falcarius among the Coelurosauria.

Similar content being viewed by others

References

  1. Maryanska, T. in The Complete Dinosaur (eds Farlow, J. O. & Brett-Surman, M. K.) 234–241 (Indiana Univ. Press, Bloomington, 1997)

    Google Scholar 

  2. Clark, J. M., Maryanska, T. & Barsbold, R. in The Dinosauria II (eds Weishampel, D. B., Dodson, P. & Osmolska, H.) 151–164 (Univ. California Press, Berkeley, 2004)

    Book  Google Scholar 

  3. Xu, X., Tang, Z.-L. & Wang, X.-L. A therizinosauroid dinosaur with integumentary structures from China. Nature 399, 350–354 (1999)

    Article  ADS  CAS  Google Scholar 

  4. Kirkland, J. I., et al. in Vertebrate Paleontology in Utah (ed. Gillette, D.) 201–217 (Utah Geol. Surv. Misc. Pub. 99-1, Salt Lake City, 1999)

    Google Scholar 

  5. Kirkland, J. I. Utah's newly recognized dinosaur record from the Early Cretaceous Cedar Mountain Formation. Utah Geol. Surv. Surv. Notes 37, 1–5 (2005)

    MathSciNet  Google Scholar 

  6. Clark, J. M., Perle, A. & Norell, M. A. The skull of Erlicosaurus andrewsi, a Late Cretaceous ‘segnosaur’ (Theropoda: Therizinosauridae) from Mongolia. Am. Mus. Novit. 3115, 1–39 (1994)

    Google Scholar 

  7. Kirkland, J. I. & Wolfe, D. G. A therizinosaurid (Dinosauria: Theropoda) braincase from the middle Turonian (Cretaceous) of North America. J. Vertebr. Paleont. 21, 68A (2001)

    Article  Google Scholar 

  8. Sues, H.-D. On Chirostenotes, a Late Cretaceous oviraptorosaur (Dinosauria: Theropoda) from western North America. J. Vertebr. Paleont. 17, 698–716 (1997)

    Article  Google Scholar 

  9. Senter, P., Barsbold, R., Britt, B. B. & Burnham, D. A. Systematics and evolution of Dromaeosauridae (Dinosauria, Theropoda). Bull. Gunma Mus. Nat. Hist. 8, 1–20 (2004)

    Google Scholar 

  10. Xu, X., Cheng, Y.-N., Wang, X.-L. & Chang, C.-H. An unusual oviraptorosaurian dinosaur from China. Nature 419, 291–293 (2002)

    Article  ADS  CAS  Google Scholar 

  11. Dong, Z. & Yu, H. in Sino-Japanese Silk Road Dinosaur Expedition (ed. Dong, Z.) 90–95 (China Ocean Press, Beijing, 1997)

    Google Scholar 

  12. Russell, D. A. & Dong, Z.-M. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People's Republic of China. Can. J. Earth Sci. 30, 2107–2127 (1993)

    Article  ADS  Google Scholar 

  13. Kirkland, J. I. & Wolfe, D. G. First definitive therizinosaurid (Dinosauria; Theropoda) from North America. J. Vertebr. Paleont. 21, 410–414 (2001)

    Article  Google Scholar 

  14. Osmolska, H., Currie, P. J. & Barsbold, R. in The Dinosauria II (eds Weishampel, D. B., Dodson, P. & Osmolska, H.) 165–183 (Univ. California Press, Berkeley, 2004)

    Book  Google Scholar 

  15. Zhang, X.-H. et al. A long-necked therizinosauroid dinosaur from the Upper Cretaeous Iren Dabasu Formation of Nei Mongol, People's Republic of China. Vertebr. PalAsiatica 10, 282–290 (2001)

    Google Scholar 

  16. Perle, A. Segnosauridae—a new family of theropods from the Late Cretaceous of Mongolia. Trans. Joint Soviet-Mongolian Palaeont. Exped. 8, 45–55 (1979)

    Google Scholar 

  17. Barsbold, R. New information on Therizinosaurus (Therizinosauridae, Theropoda). Trans. Joint Soviet-Mongolian Palaeont. Exped. 3, 76–92 (1976)

    Google Scholar 

  18. Perle, A. A new segnosaurid from the Upper Cretaceous of Mongolia. Trans. Joint Soviet-Mongolian Palaeont. Exped. 15, 45–55 (1981)

    Google Scholar 

  19. Mader, B. J. & Bradley, R. L. A redescription and revised diagnosis of the syntypes of Alectrosaurus olseni . J. Vertebr. Paleont 9, 41–55 (1989)

    Article  Google Scholar 

  20. Xu, X. et al. A new therizinosauroid (Dinosauria, Theropoda) from the Upper Cretaceous Iren Dabasu Formation of Nei Mongol. Vertebr. PalAsiatica 40, 228–240 (2002)

    Google Scholar 

  21. Perle, A. On a new finding of the hindlimb of Therizinosaurus sp. from the Late Cretaceous of Mongolia. Probl. Geol. Mongol. 5, 94–98 (1982)

    Google Scholar 

  22. Gauthier, J. A. Saurischian monophyly and the origin of birds. Mem. Calif. Acad. Sci. 8, 1–55 (1986)

    Google Scholar 

  23. Holtz, T. R. A new phylogeny of the carnivorous dinosaurs. Gaia 15, 5–61 (2000)

    Google Scholar 

  24. Norell, M. A., Clark, J. M. & Makovicky, P. J. in New Perspectives on the Origin and Early Evolution of Birds (eds Gauthier, J. & Gall, L. F.) 49–67 (Peabody Museum of Natural History, New Haven, 2001)

    Google Scholar 

  25. Rauhut, O. W. M. The interrelationships and evolution of basal theropod dinosaurs. Spec. Pap. Palaeont. 69, 1–213 (2003)

    Google Scholar 

  26. Paul, G. S. The segnosaurian dinosaurs: relics of the prosauropod–ornithischian tranisition. J. Vertebr. Paleont. 4, 507–515 (1984)

    Article  Google Scholar 

  27. Xu, X., Zhao, X. & Clark, J. M. A new therizinosaur from the Lower Jurassic Lufeng Formation of Yunnab, China. J. Vertebr. Paleont. 21, 477–483 (2001)

    Article  Google Scholar 

  28. Swofford, D. L. PAUP* Phylogenetic Analysis Using Parsimony (*and Other Methods), version 4.0b10 (Sinauer Associates, Sunderland, Massachusetts, 2002)

    Google Scholar 

Download references

Acknowledgements

We thank X. Xu, Z. Dong, P. Sereno and M. Norell for access to reference material; G. Paul for executing the skeletal reconstruction of Falcarius; The Utah Friends of Paleontology, the Utah Museum of Natural History, and H. and P. Bollan for assistance in the field and the laboratory; M. Hayden, M. Christopher, M. Suarez and C. Suarez for overseeing the volunteers in the field; J. R. Scandizzo for introductions to the site discoverer L. Walker of Moab, Utah; R. W. Gaston for providing research casts; D. Smith for comments on theropod braincase anatomy; and J. Harris, M. Hayden, M. Lowe and M. Hylland for reviewing the manuscript. Excavations were conducted under a US Bureau of Land Management permit. Funding was provided by the Utah Geological Survey, Discovery Channel Quest Grants, Paleoscene, to J.I.K. and the NSF to J.M.C.

Author information

Authors and Affiliations

  1. Utah Geological Survey, PO Box 146100, Salt Lake City, Utah, 84114-6100, USA

    James I. Kirkland & Donald D. DeBlieux

  2. Utah Museum of Natural History and Department of Geology and Geophysics, University of Utah, 1390 E. Presidents Circle, Salt Lake City, Utah, 84112-0050, USA

    Lindsay E. Zanno & Scott D. Sampson

  3. George Washington University, Washington DC, 20052, USA

    James M. Clark

Authors
  1. James I. Kirkland
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Lindsay E. Zanno
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Scott D. Sampson
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. James M. Clark
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Donald D. DeBlieux
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to James I. Kirkland.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Notes

This file includes the character list and data matrix, and also contains additional references used in the character list. (DOC 107 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kirkland, J., Zanno, L., Sampson, S. et al. A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah. Nature 435, 84–87 (2005). https://doi.org/10.1038/nature03468

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature03468

  • Springer Nature Limited

This article is cited by

Search

Navigation