Animals - Trachodon and Maiasaurus ), ceratopsians (such as...

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Animals The dinosaurs have traditionally been classified into two distinct taxonomic classes, the saurischia (lizard-hipped) and ornithischia (bird-hipped). This divergence was accomplished by the close of the Triassic. The ancestors of dinosaurs were some unspecified thecodont earlier in the Triassic. The Saurischia, which includes Dilophosaurus and Coelophysis , has two main groups, the theropods and the sauropods. The theropods were bipedal carnivores that included the famous Velociraptor and Tyrannosaurus rex as well as birds. Sauropods and similar forms were quadrupedal, mostly herbovorous forms that include the giants of the Jurassic: Apatosaurus , Diplodicus , and Brachiosaurus . The recently discovered Arizona dinosaur Sonorasaurus belongs in this group as well. Ornithischians were all herbivourous, with some retaining a bipedal gait, and others returning to four legs, and included: the ornithopods (such as
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Unformatted text preview: Trachodon and Maiasaurus ), ceratopsians (such as Triceratops ), and the stegosaurians (including Stegosaurus and Ankylosaurus ). Mammals also evolved during the Triassic, at about the same time as the dinosaurs. However, Triassic mammals were small and inconsequential components of the Triassic ecosystems. The Triassic World Pangaea reached its greatest extent during the Triassic. The conditions from the Permian (dry continental interiors, few if any shallow marginal continental seas) continued. Around the middle of the Triassic the breakup of Pangaea began, with the supercontinent separating into two landmasses, Gondwana in the south (composed of the future continents of South America, Africa, India, Antarctica, and Australia) and Laurasia in the north (Asia and North America). The breakup of Pangaea also resulted in mountain-building along the western edges of North and South America....
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Animals - Trachodon and Maiasaurus ), ceratopsians (such as...

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