Placochelys Explained

Placochelys (from Greek, Modern (1453-);: plax, plakos, "plate" and Greek, Modern (1453-);: chelys, "tortoise")^[1] is an extinct genus of placodont reptiles erected by Otto Jaekel in 1902.

Fossil records

Fossils of Placochelys dates back to the Triassic period (age range: 221.5 to 205.6 million years ago). They have been found in Germany, Austria, Hungary and Italy.^[2]

Species

This genus includes only one species:

• Placochelys placodonta Jaekel, 1902 (from Upper Ladinian of Hungary)

Description

Placochelys looked remarkably similar to a sea turtle, and grew to about 90cm (40inches) in length. It had a flat turtle-like carapace covered with knobbly plates, and a compact triangular skull. 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 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.^[3]

Bibliography

• Jaekel O. 1902. Über Placochelys n. g. und ihre Beeutung fur die Stammesgeschichte der Schildkroten: Neues Jahrbuch für 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.

External links

• The cranial anatomy of Placochelys placodonta Jaekel, 1902, and a review of the Cyamodontoidea (Reptilia, Placodonta) (2001)
• PLACODONTS: THE BIZARRE ‘WALRUS-TURTLES’ OF THE TRIASSIC

Notes and References

1. Book: Colbert . Edwin H. (Edwin Harris) . Knight . Charles Robert . The dinosaur book: the ruling reptiles and their relatives . 1951 . McGraw-Hill . New York . 153 .
2. http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=36537 Paleobiology Database
3. Book: Palmer, D.. 1999 . The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. Marshall Editions. London. 71. 1-84028-152-9.