Pareiasaur

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iPareiasauridae Fossil range: Middle to Late Permian
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Superclass: Tetrapoda Class: Sauropsida/Reptilia Subclass: Anapsida/Parareptilia Order: Procolophonia Family: Pareiasauridae Lydekker, 1889
Genera
Bradysaurus Nochelesaurus Embrithosaurus Deltavjatia Velosauria Shihtienfenia Pareiasuchus Pareiasaurus Scutosaurus Elginia Nanopareia Anthodon

The Pareiasaurs - family Pareiasauridae - are a group of medium-sized to large (60 cm to 3 meters long), stocky, early, reptilian herbivores, that flourished during the Permian period. These ungainly-looking animals had very large bodies (weights of 600 kg would not have been unusual), strong limbs, broad feet, and short tails. They were protected with bony scutes (osteoderms) set in the skin, as a defense against predators. But the most unusual thing about them were the heavy skulls ornamented with strange knobs and ridges.

The leaf-shaped multi-cusped teeth resemble those of iguanas, caseids, and other reptilian herbivores. This dentition, together with the deep capacious body (which would have housed an extensive digestive tract) indicate that these fearsome-looking animals were in fact inoffensive herbivores.

Lee 1997 has argued that Pareiasaurs evolved into turtles. They had turtle-like skull features, and in several genera the scutes had developed into bony plates, possibly the precursors of a turtle shell. However, critics have pointed out problems in this view, such as the non-homology between parieasaur scutes and the turtle shell.

[edit] References / Links

• Carroll, R. L., (1988), Vertebrate Paleontology and Evolution, W.H. Freeman & Co. New York, p.205
• deBraga, M. & Rieppel, O. (1997) Reptile phylogeny and the interrelationships of turtles, Zool. J. Linnean Soc. 120: 281-354.
• Kuhn, O, 1969, Cotylosauria, part 6 of Handbuch der Palaoherpetologie (Encyclopedia of Palaeoherpetology), Gustav Fischer Verlag, Stuttgart & Portland
• Laurin, M. (1996), "Introduction to Pareiasauria - An Upper Permian group of Anapsids"
• Lee, M.S.Y. (1997), Pareiasaur phylogeny and the origin of turtles. Zool. J. Linnean Soc., 120: 197-280
• Mikko's Phylogeny Archive Hallucicrania - Pareiasauriformes
• Palaeos Anapsida: Hallucicrania