Title: The dinosaur book : the ruling reptiles and their relatives
Identifier: dinosauruli13colb (find matches)
Year: 1945 (1940s)
Authors: Colbert, Edwin H. (Edwin Harris), 1905-2001; Germann, John C
Subjects: Dinosaurs; Reptiles, Fossil
Publisher: New York, N. Y. : American Museum of Natural History
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: IMLS / LSTA / METRO

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From "grandfather" Seytnouria, two general lines of reptiles descended. In one, the ani- mals remained small, like Labidosaurus. In the other, there was a tendency to giantism, as may be seen in Diadectes from North America and in the large pariasaurs from the Old World, one of which is shown opposite Restorations by John C. Germann an inheritance from the solid, bony skulls of their labyrinthodont ancestors. Of these anapsids, the first to appear were reptiles belonging to the order known as the Co- tylosauria (ko-TiLE-o-sawr-e-ya), of which group Seymouria is perhaps the most primi- tive, though not the earliest representative. The cotylosaurs evolved through Permian and Triassic times and then become extinct. Their evolution was divided along three lines of development. First there were the small primitive forms of Carboniferous and Permian age closely related to the "grand- father reptile," Seijmouria. These are often known as the seymouriamorphs. Then there was a line of small Permian cotylosaurs, showing certain specializations, known as the labidosaurs (LAB-i-do-sawrs) or capto- rhinomorphs (kap-to-RiNE-o-morfs). Fi- nally, the third group of cotylosaurs, known as the diadectomorphs (dye-a-DEKT-o- morfs), consisted of quite large reptiles living in the Permian period, and small, highly specialized survivors persisting through the Triassic period. Labidosaurus was small, like Seymouria. It had the long body and the sprawling, weak limbs of the primitive reptile. The skull, as in all anapsids, was roofed over by solid bone, and was abruptly truncated be- hind. A characteristic feature of this animal was the overhung, or hooked upper jaw. Diadectes (dye-a-DEKT-eez) was a rather large Permian reptile, some five or six feet in length. The legs were sprawling, as in the other primitive anapsids, so that this animal must have been rather clumsy when walking. Diadectes seemingly was a plant- eating reptile, for the teeth were blunt and peglike, and not at all suited to catching animals as were the pointed, spikelike teeth of Seijmouria and Labidosaurus. A remark- able feature of Diadectes was the large pineal opening on the top of the skull, showing that this reptile had a very large "pineal eye"—an organ sensitive to light, which still persists in a much reduced form in the recent lizards and the tuatara (Sphenodon) of New Zealand. Closely related to the American diadectids were the Permian pariasaurs (par-EYE-a-sawrs) of South Africa and Russia. These were really massive reptiles, as big as small cattle. Like the other large cotylosaurs they were seemingly plant eaters, large, heavy, and sluggish. They had 50

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