Hairy Museum of Natural History

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• Chinlechelys tenertesta
  Life restoration by Mary Sundstrom
  

• New Turtle: Chinlechelys tenertesta
• Name Means: Delicately-shelled Chinle Turtle
• Relations: Basal Turtle
• Holotype: NMMNH P-16697, partial skeleton including pieces of carapace, plastron, neck spine, etc.
• Location: New Mexico, U.S.A.
• Age: Late Triassic, ~205,000,000 years ago
• Info: The fragments that make up the holotype of Chinlechelys include one and one-half dorsal vertebrae that are fused to a thin bit of shell in a distinctively turtle-like manner. Other pieces include a chunk of the plastron, or lower shell, and a piece from the rear of the carapace (upper shell) with bits of rib on the underside. Two spikes of armor were found that may have protected the animal’s neck—similar spikes adorned the necks of more completely known Triassic turtles like the European Proganochelys.
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  The more impressive bits of Chinlechelys on display at the NMMNHS.
• Joyce et al. consider Chinlechelys to be something of a “turtle-in-progress.” Its shell is extremely thin (1 to 3mm thick) and, unlike all other turtles, its ribs do not appear to be tightly fused to its carapace. This fossil could help resolve a long-standing controversy in turtle evolution—did the turtle shell evolve as the ribs widened and fused together into a dome-like shell, or did rows of armor plating in the skin expand until they fused together and integrated with the ribs and vertebrae for support? According to its describers, the thin shell and loosely integrated ribs of Chinlechelys provide compelling evidence for the latter scenario.
• Reference: Joyce, W. G., Lucas, S. G., Scheyer, T. M., Heckert, A. B., and Hunt, A. P., 2008. A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell Proceedings of the Royal Society B Published online (FirstCite). DOI: 10.1098/rspb.2008.1196
• Elsewhere on the Web:
  • New Scientist: Fossil Reveals How the Turtle Got Its Shell
  • Chinleana: New “Proto-Turtle” from the Late Triassic of New Mexico
  • Dracovenator: Good News Everyone!

—Matt Celeskey.

File under: Reptiles, Triassic.