A basal troodontid from the Early Cretaceous of China

Abstract

Troodontid dinosaurs form one of the most avian-like dinosaur groups1,2,3,4,5. Their phylogenetic position is hotly debated, and they have been allied with almost all principal coelurosaurian lineages6,7,8,9,10,11,12,13. Here we report a basal troodontid dinosaur, Sinovenator changii gen. et sp. nov., from the lower Yixian Formation of China. This taxon has several features that are not found in more derived troodontids, but that occur in dromaeosaurids and avialans. The discovery of Sinovenator and the examination of character distributions along the maniraptoran lineage indicate that principal structural modifications toward avians were acquired in the early stages of maniraptoran evolution.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: Select elements of Sinovenator changii.
Figure 2: A proposed coelurosaurian phylogeny that is based on the strict consensus of the 336 equally most parsimonious trees (tree length, 576; consistency index, 0.43; retention index, 0.70).

References

  1. 1

    Currie, P. J. Cranial anatomy of Stenonychosaurus inequalis (Saurischia, Theropoda) and its bearing on the origin of birds. Can. J. Earth Sci. 22, 1643–1658 (1985).

  2. 2

    Currie, P. J. Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria: Saurischia). J. Vert. Paleontol. 7, 72–81 (1987).

  3. 3

    Currie, P. J. & Zhao, X.-J. A new troodontid (Dinosauria, Theropoda) braincase from the Dinosaur Park Formation (Companian) of Alberta. Can. J. Earth Sci. 30, 2224–2230 (1993).

  4. 4

    Osmolska, H. & Barsbold, R. in The Dinosauria (eds Weishampel, D. B., Dodson, P. & Osmolska, H.) 259–268 (Univ. California Press, Berkeley, 1990).

  5. 5

    Russell, D. A. & Dong, Z.-M. A nearly complete skeleton of a new troodontid dinosaur from the Early Cretaceous of the Ordos Basin, Inner Mongolia, People's Republic of China. Can. J. Earth Sci. 30, 2163–2173 (1993).

  6. 6

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

  7. 7

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

  8. 8

    Holtz, T. R. Jr The phylogenetic position of the Tyrannosauridae: implications for theropod systematics. J. Paleontol. 68, 1100–1117 (1994).

  9. 9

    Forster, C. A., Sampson, S. D., Chiappe, L. M. & Krause, D. W. The theropod ancestry of birds: new evidence from the Late Cretaceous of Madagascar. Science 279, 1915–1919 (1998).

  10. 10

    Makovicky, P. & Sues, H.-D. Anatomy and phylogenetic relationships of the theropod dinosaur Microvenator celer from the Lower Cretaceous of Montana. Am. Mus. Novitates 3240, 1–27 (1998).

  11. 11

    Xu, X., Wang, X.-L. & Wu, X.-C. A dromaeosaurid dinosaur with a filamentous integument from the Yixian Formation of China. Nature 401, 262–266 (1999).

  12. 12

    Sereno, P. C. The evolution of dinosaurs. Science 284, 2137–2147 (1999).

  13. 13

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

  14. 14

    Wang, X.-L. et al. Stratigraphic sequence and vertebrate bearing beds of the lower part of the Yixian Formation in Sihetun and neighbouring area, western Liaoning, China. Vert. PalAsiatica 36, 81–101 (1998).

  15. 15

    Xu, X., Wang, X.-L. & You, H.-L. A primitive ornithopod from the Early Cretaceous Yixian Formation of Liaoning. Vert. PalAsiatica 38, 318–325 (2000).

  16. 16

    Li, J.-L., Wang, Y., Wang, Y.-Q. & Li, C.-K. A new family of primitive mammal from the Mesozoic of western Liaoning, China. Chinese Sci. Bull. (Engl.) 46, 782–786 (2001).

  17. 17

    Chatterjee, S. The Rise of Birds (John Hopkins Univ. Press, Baltimore, 1997).

  18. 18

    Barsbold, R. & Osmólska, H. The skull of Velociraptor (Theropoda) from the late Cretaceous of Mongolia. Acta Palaeontol. Polon. 44, 189–219 (1999).

  19. 19

    Norell, M. A., Makovicky, P. & Clark, J. M. A new troodontid theropod from Ukhaa Tolgod, Mongolia. J. Vert. Paleontol. 20, 7–11 (2000).

  20. 20

    Barsbold, R., Osmólska, H. & Kurzanov, S. On a new troodontid (Dinosauria: Theropoda) from the Early Cretaceous of Mongolia. Acta Palaeontol. Polon. 32, 121–132 (1997).

  21. 21

    Walker, A. D. in The Beginnings of Birds (eds Hecht, M. K., Ostrom, J. H., Viohl, H. & Wellnhofer, P.) 123–134 (Freunde des Jura-Museums, Eichstatt, 1985).

  22. 22

    Witmer, L. M. The craniofacial air sac system of Mesozoic birds (Aves). Zool. J. Linn. Soc. 100, 327–378 (1990).

  23. 23

    Chiappe, L. M., Norell, M. A. & Clark, J. M. The skull of a relative of the stem-group bird Mononykus. Nature 392, 275–278 (1998).

  24. 24

    Barsbold, R. Saurornithoididae, a new family of small theropod dinosaurs from Central Asia and North America. Palaeontol. Polon. 30, 5–22 (1974).

  25. 25

    Xu, X., Zhou, Z.-H. & Wang, X.-L. The smallest known non-avian theropod dinosaur. Nature 408, 705–708 (2000).

  26. 26

    Norell, M. A. & Makovicky, P. J. Important features of the dromaeosaurid skeleton II: information from newly collected specimens of Velociaptor mongoliensis. Am. Mus. Novitates 3282, 1–45 (1999).

  27. 27

    Xu, X. & Wang, X.-L. Troodontid-like pes in the dromaeosaurid Sinornithosaurus. (Spec. Publ.) 179–188 (Paleontology Society of Korea, Seoul, 2000).

  28. 28

    Kurzanov, S. M. Braincase structure in the carnosaur Itemirus n. gen. and some aspects of the cranial anatomy of dinosaurs. Paleontol. Zh. 1976, 127–137 (1976).

  29. 29

    Holtz, T. R. Jr Phylogenetic taxonomy of the Coelurosauria (Dinosauria: Theropoda). J. Paleontol. 70, 536–538.

  30. 30

    Perle, A., Norell, M. & Clark, J. A new maniraptoran theropod Achillobator giganticus (Dromaeosauridae) from the Upper Cretaceous of Burkhant, Mongolia. (Dept Geol., Natl Univ. Mongolia, Ulaanbaatar, 1999).

Download references

Acknowledgements

We thank Z.-H. Zhou for help; H.-J. Wang and B. Long for specimen preparation; R.-S. Li for drawings; M. Ellison for photographs; and members of the Liaoxi expedition team of the IVPP. This work was supported by grants from the Special Funds for Major State Basic Research Projects of China, the National Geographic Society, the Chinese Natural Science Foundation and the Chinese Academy of Sciences. M.A.N. and P.J.M. are supported by the American Museum of Natural History and the Field Museum, respectively.

Author information

Correspondence to Xing Xu.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Character list 1–206 (DOC 94 kb)

Rights and permissions

Reprints and Permissions

About this article

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.