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| '''''Mesodermochelys''''' is an ] ] of ] that existed during the Late ], from the ] to the ] of what today is Japan.<ref name="Hirayama, 2007"> Hirayama R. 2007. Cranial morphology of ''Mesodermochelys'' (Chelonioidea; Testudines) from the Late Cretaceous of Japan. ''Journal of Vertebrate Paleontology'' '''27''' (3): 89A.</ref> The genus was discovered and |
'''''Mesodermochelys''''' is an ] ] of ] that existed during the Late ], from the ] to the ] of what today is Japan.<ref name="Hirayama, 2007"> Hirayama R. 2007. Cranial morphology of ''Mesodermochelys'' (Chelonioidea; Testudines) from the Late Cretaceous of Japan. ''Journal of Vertebrate Paleontology'' '''27''' (3): 89A.</ref> The genus was discovered and given its ] by Ren Hirayama and Tsutomu Chitoku in 1996,<ref name="Hirayama et al., 2006"> Hirayama R, Fujii A, Takahashi K. 2006. A dermochelyid sea turtle from the Upper Cretaceous (Late Campanian) Izumi Group of Shionoe, Takamatsu, Kagawa Prefecture, Western Japan. ''Fossils (Palaeontological Society of Japan)'' '''80''': 17-20.</ref> and contains one species, the ] ''M. undulatus''.<ref name="Hirayama & Chitoku, 1996"/> Studies of the skull of ''M. undulatus'' indicate that it was a primitive cheloniid that was closely-related to the ].<ref name="Hirayama, 2007"/> It has been described as the best representative of ] ].<ref name="Hirayama & Chitoku, 1996"/> | ||
| ==Description== | ==Description== | ||
Revision as of 22:26, 27 July 2008
| Mesodermochelys Temporal range: Late Cretaceous | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Sauropsida |
| Order: | Testudines |
| Suborder: | Cryptodira |
| Family: | Dermochelyidae |
| Genus: | Mesodermochelys Hirayama & Chitoku, 1996 |
| Species | |
| |
Mesodermochelys is an extinct genus of sea turtle that existed during the Late Cretaceous, from the Santonian to the Campanian of what today is Japan. The genus was discovered and given its binomial name by Ren Hirayama and Tsutomu Chitoku in 1996, and contains one species, the type species M. undulatus. Studies of the skull of M. undulatus indicate that it was a primitive cheloniid that was closely-related to the Protostegidae. It has been described as the best representative of Mesozoic dermochelyiids.
Description
Like other dermocheyliids, Mesodermochelys had elongated front flippers. One fossil found in Japan's Kagawa Prefecture had a carapace estimated to be 1.3 metres in length. Only the neural or spinal scutes, or individual plates, of the carapace are well-grooved.
Specimens
In October 2005, Yoshiyuki Hattori uncovered a skull of Mesodermochelys, in the Santonian-age Yezo Group in the Hokkaido Prefecture. Though weathering had caused the absence of most of the dermal roofing elements on the skull, it is regarded as being the best-preserved specimen of a Mesodermochelys skull. The skull was donated to the Hokkaido Museum, where a study using formic acid to etch the fossil from its matrix revealed certain characteristics about the skull. Other, less complete specimens of Mesodermochelys skulls and jaws have been found in the Maastrichtian type locality of the Hokkaido Prefecture. A total of fifteen specimens have been uncovered, including an almost-complete shell.
References
- ^ Hirayama R, Chitoku T. 1996. Family Dermochelyidae (Superfamily Chelonioidea) from the Upper Cretaceous of North Japan. Transactions and proceedings of the Palaeontological Society of Japan. New series 184: 597-622.
- ^ Hirayama R. 2007. Cranial morphology of Mesodermochelys (Chelonioidea; Testudines) from the Late Cretaceous of Japan. Journal of Vertebrate Paleontology 27 (3): 89A.
- ^ Hirayama R, Fujii A, Takahashi K. 2006. A dermochelyid sea turtle from the Upper Cretaceous (Late Campanian) Izumi Group of Shionoe, Takamatsu, Kagawa Prefecture, Western Japan. Fossils (Palaeontological Society of Japan) 80: 17-20.