An ancestral turtle from the Late Triassic of southwestern China (original) (raw)

Nature volume 456, pages 497–501 (2008)Cite this article

Abstract

The origin of the turtle body plan remains one of the great mysteries of reptile evolution. The anatomy of turtles is highly derived, which renders it difficult to establish the relationships of turtles with other groups of reptiles. The oldest known turtle, Proganochelys from the Late Triassic period of Germany1, has a fully formed shell and offers no clue as to its origin. Here we describe a new 220-million-year-old turtle from China, somewhat older than Proganochelys, that documents an intermediate step in the evolution of the shell and associated structures. A ventral plastron is fully developed, but the dorsal carapace consists of neural plates only. The dorsal ribs are expanded, and osteoderms are absent. The new species shows that the plastron evolved before the carapace and that the first step of carapace formation is the ossification of the neural plates coupled with a broadening of the ribs. This corresponds to early embryonic stages of carapace formation in extant turtles, and shows that the turtle shell is not derived from a fusion of osteoderms. Phylogenetic analysis places the new species basal to all known turtles, fossil and extant. The marine deposits that yielded the fossils indicate that this primitive turtle inhabited marginal areas of the sea or river deltas.

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References

  1. Gaffney, E. S. The comparative osteology of the Triassic turtle Proganochelys . Bull. Am. Mus. Nat. Hist. 194, 1–263 (1990)
    Google Scholar
  2. Wang, L. et al. Biostratigraphy of Triassic marine reptiles in southwest Guizhou and its adjacent area. Acta Geol. Sin. 75, 349–353 (2001)
    Google Scholar
  3. Wang, X. et al. The Late Triassic black shales from the Guanling area. Guizhou Province, south-west China: a unique marine reptile and pelagic crinoid fossil Lagerstätte. Palaeontology 51, 27–61 (2008)
    Article Google Scholar
  4. Wang, X., Hagdorn, H. & Wang, C. Pseudoplanktonic lifestyle of the Triassic crinoid Traumatocrinus from southwest China. Lethaia 39, 187–193 (2006)
    Article Google Scholar
  5. Jiang, D. et al. Guanling biota: a marker of Triassic biotic recovery from end-Permian extinction in the ancient Guizhou sea. Acta Geol. Sin. 79, 729–738 (2005)
    Article Google Scholar
  6. Joyce, W. J. Phylogenetic relationships of Mesozoic turtles. Bull. Peabody Mus. Nat. Hist. 48, 3–102 (2007)
    Article Google Scholar
  7. Reisz, R. R. & Laurin, M. Owenetta and the origin of turtles. Nature 349, 324–326 (1991)
    Article ADS Google Scholar
  8. Lee, M. S. Y. The origin of the turtle body plan: bridging a famous morphological gap. Science 261, 1716–1720 (1993)
    Article ADS CAS Google Scholar
  9. Lee, M. S. Y. Correlated progression and the origin of turtles. Nature 379, 812–815 (1996)
    Article ADS CAS Google Scholar
  10. Rieppel, O. & deBraga, M. Turtles as diapsid reptiles. Nature 384, 453–455 (1996)
    Article ADS CAS Google Scholar
  11. Rieppel, O. & Reisz, R. R. The origin and early evolution of turtles. Annu. Rev. Ecol. Syst. 30, 1–22 (1999)
    Article Google Scholar
  12. Rieppel, O. Studies on skeleton formation in reptiles. Patterns of ossification in the skeleton of Chelydra serpentina Linnaeus (Reptilia, Testudines). J. Zool. 231, 487–509 (1993)
    Article Google Scholar
  13. Scheil, C. A. Osteology and skeletal development of Apalone spinifera (Reptilia: Testudines: Trionychidae). J. Morphol. 256, 42–78 (2003)
    Article Google Scholar
  14. Sheil, C. A. & Greenbaum, E. Reconsideration of skeletal development of Chelydra serpentina (Reptilia: Testudinata: Chelydridae): evidence for intraspecific variation. J. Zool. 265, 235–267 (2005)
    Article Google Scholar
  15. Procter, J. B. A study of the remarkable tortoise, Testudo loveridgii Blgr, and the morphogeny of the chelonian carapace. Proc. Zool. Soc. Lond. 1922, 483–526 (1922)
    Article Google Scholar
  16. Gilbert, S. F., Loredo, G. A., Brukman, A. & Burke, A. C. Morphogenesis of the turtle shell: the development of a novel structure in tetrapod evolution. Evol. Dev. 3, 47–58 (2001)
    Article CAS Google Scholar
  17. Scheyer, T. M., Brüllmann, B. & Sánchez-Villagra, M. R. The ontogeny of the shell in side-necked turtles, with emphasis on the homologies of costal and neural bones. J. Morphol. 269, 1008–1021 (2008)
    Article Google Scholar
  18. Yntema, C. L. A series of stages in the embryonic development of Chelydra serpentina . J. Morphol. 125, 219–252 (1968)
    Article CAS Google Scholar
  19. Kälin, J. Zur Morphogenese des Panzers bei den Schildkröten. Acta Anat. 1, 144–176 (1945)
    Article Google Scholar
  20. Gilbert, S. F., Cebra-Thomas, J. A. & Burke, A. C. in Biology of Turtles (eds Wyneken, J., Godfrey, M. H. & Bels, V.) 1–16 (CRC Press, 2008)
    Google Scholar
  21. Zangerl, R. The homology of the shell elements in turtles. J. Morphol. 65, 383–406 (1939)
    Article Google Scholar
  22. Moss, M. L. Comparative histology of dermal sclerifications in reptiles. Acta Anat. 73, 510–533 (1969)
    Article CAS Google Scholar
  23. Zylbernerg, L. & Castanet, J. New data on the structure and growth of the osteoderms in the reptile Anguis fragilis L. (Anguidae, Squamata). J. Morphol. 186, 327–342 (1985)
    Article Google Scholar
  24. Lervrat-Calviac, V. & Zylberg, L. The structure of the osteoderms in the gecko: Tarentola mauritanica . Am. J. Anat. 176, 437–446 (1986)
    Article Google Scholar
  25. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874–893 (2004)
    Article Google Scholar
  26. Maine, R. P., de Ricqlès, A., Horner, J. R. & Padian, K. The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs. Paleobiology 31, 291–314 (2005)
    Article Google Scholar
  27. Vickaryous, M. K. & Hall, B. K. Development of the dermal skeleton in Alligator mississippiensis (Archosauria, Crocodylia) with comments on the homology of osteoderms. J. Morphol. 269, 398–422 (2008)
    Article Google Scholar
  28. Scheyer, T. M. & Sander, P. M. Shell bone histology indicates terrestrial paleoecology of basal turtles. Proc. R. Soc. B 274, 1885–1893 (2007)
    Article Google Scholar
  29. Versluys, J. Über die Phylogenie des Panzers der Schildkröten und über die Verwandtschaft der Lederschildkröte (Dermochelys coriacea). Paläontol. Z. 1, 321–347 (1914)
    Article Google Scholar
  30. Joyce, W. G. & Gauthier, J. A. Paleoecology of Triassic stem turtles sheds new light on turtle origins. Proc. R. Soc. B 271, 1–5 (2003)
    Article Google Scholar

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Acknowledgements

We thank Z. Tang for his help in collecting the specimens; J. Ding and H. Zhou for preparing the specimens; and W. Gao for taking the photos. C.L. and L.-T.W. were supported by the Major Basic Research Projects (2006CB806400) of the Ministry of Science and Technology of China, the National Natural Science Foundation (40772015, 40121202) of China (NNSFC) and a special grant for fossil excavation and preparation of the Chinese Academy of Sciences. X.-C.W. was supported by grants from the Canadian Museum of Nature (RS 34), NNSFC 40772015 and the CAS/SAFEA International Partnership Program for Creative Research Teams. O.R. was supported by a stipend from M. Tang.

Author Contributions C.L. designed the project. C.L., X.-C.W., O.R., L.-T.W. and L.-J.Z. performed the research. C.L., X.-C.W. and O.R. contributed to the writing.

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Authors and Affiliations

  1. Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of SciencesPO Box 643, Beijing 100044, China ,
    Chun Li
  2. Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada ,
    Xiao-Chun Wu
  3. Department of Geology, The Field Museum, 1400 South Lake Shore Drive, Chicago, Illinois 60605-2496, USA,
    Olivier Rieppel
  4. Geological Survey of Guizhou Province, Guiyang 550005, China
    Li-Ting Wang
  5. Zhejiang Museum of Nature History, Hangzhou 310012, China
    Li-Jun Zhao

Authors

  1. Chun Li
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  2. Xiao-Chun Wu
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  3. Olivier Rieppel
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  4. Li-Ting Wang
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  5. Li-Jun Zhao
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Corresponding authors

Correspondence toChun Li or Xiao-Chun Wu.

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Li, C., Wu, XC., Rieppel, O. et al. An ancestral turtle from the Late Triassic of southwestern China.Nature 456, 497–501 (2008). https://doi.org/10.1038/nature07533

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Editorial Summary

Turning turtle: how proto-turtles gained a shell

A well preserved 220-million-year-old fossil from marine deposits of the Late Triassic of Guizhou in southwest China sheds light on the intermediate steps in the acquisition of the unique turtle body-plan. Transitional forms are scarce in this lineage, making this transition one of the mysteries of reptile evolution. The find is the most primitive turtle known. It has a fully developed plastron, the ventral dermal armour, evolved before the carapace, the dorsal (upper) part of the shell structure. In this fossil the carapace consists of neural plates only. This suggest that the carapace developed via ossification of the neural plates and broadening of the ribs — a sequence that echoes the developmental pattern in young turtles today.

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