''Placochelys'' ('flat-plate turtle") is an extinct genus of placodont

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s erected by

Otto Jaekel Otto Max Johannes Jaekel (21 February 1863 – 6 March 1929) was a German paleontologist and geologist. Biography Jaekel was born in Neusalz (Nowa Sól), Prussian Silesia, the son of a builder and the youngest of seven children. He studied at ...

in 1902.

Fossil records

Fossils of ''Placochelys'' dates back to the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

period (age range: 221.5 to 205.6 million years ago). They have been found in Germany, Austria, Hungary and Italy.Paleobiology Database
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Species

This genus includes only one species: * ''Placochelys placodonta'' Jaekel, 1902 (from Upper

Ladinian The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic). ...

of Hungary)

Description

''Placochelys'' looked remarkably similar to a

sea turtle Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, ...

, and grew to about in length. It had a flat turtle-like carapace covered with knobbly plates, and a compact triangular

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

. Its beaked skull had powerful muscles. It had only two pairs of palatal teeth, a large posterior pair, and a small rostral pair. The specialized broad teeth on the palate, were most likely used for crushing

shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater envir ...

and hard-shelled prey. Its limbs were paddle-shaped for swimming, although, unlike modern sea turtles, they still had discernable toes, and it also had a short tail.

Gallery

File: Placochelys_BW.jpg , Life restoration of ''Placochelys'' File: Placochelyidae - Placochelys placodonta.JPG, ''Placochelys placodonta'' fossil skull, lateral view File: Placochelys placodonta.JPG , ''Placochelys placodonta'' skull seen from below File:Placochelys tooth adnet.jpg, ''Placochelys tooth'' from Adnet, Austria

Bibliography

* Jaekel O. 1902. Über Placochelys n. g. und ihre Beeutung fur die Stammesgeschichte der Schildkroten: Neues Jahrbuch fur Mineralogie, Geologie und Palaontologie, Abhandlungen, 1902: 127–144. * Mazin, J.-M. and Pinna, G. 1993. Palaeoecology of the armoured placodonts. Paleontologia Lombarda, N. S. 2: 83–91. * Rieppel O. and Zanon R.T. 1997. The interrelationships of Placodontia. Historical Biology: Vol. 12, pp. 211–227 * Yin G., in Yin, G., Zhou, X., Cao, Z., Yu, Y, and Luo, Y., 2000, A preliminary study on the Early Late Triassic marine reptiles from Guanling Guizhou, China. * Rieppel O. 2001. The Cranial Anatomy of Placochelys placodonta Jaekel, 1902, And a Review of the Cyamodontoidea (reptilia, Placodonta) Fieldiana: Geology, New Series, No. 45:1-101. * Rieppel, O., 2002, The dermal armor of the cyamodontoid placodonts (Reptilia, Sauropterygia): morphology and systematic value: Fieldiana; Geology, new series, n. 46, p. 1-41pp.

References

External links

The cranial anatomy of Placochelys placodonta Jaekel, 1902, and a review of the Cyamodontoidea (Reptilia, Placodonta) (2001)

Placodonts Middle Triassic reptiles of Europe Late Triassic reptiles of Europe Sauropterygian genera {{triassic-reptile-stub