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 Dinosaur anatomy

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PostSubject: Dinosaur anatomy   Wed Oct 12, 2016 3:23 pm

Dinosaurs are divided into 2 major groups:

1.Saurischia is one of the two basic divisions of dinosaurs. In 1888, Harry Seeley classified dinosaurs into two orders, based on their hip structure. Saurischians ('lizard-hipped' are distinguished from the ornithischians ('bird-hipped' by retaining the ancestral configuration of bones in the hip.

All carnivorous dinosaurs (the theropods) are saurischians, as are one of the two primary lineages of herbivorous dinosaurs, the sauropodomorphs. At the end of the Cretaceous Period, all saurischians except the birds became extinct. This is referred to as the Cretaceous–Paleogene extinction event. Avians (modern birds), as direct descendants of one group of theropod dinosaurs, are a sub-clade of saurischian dinosaurs in phylogenetic classification.




2. Ornithischia - they are known as the 'bird-hipped' dinosaurs because of their bird-like hip structure, even though birds actually belong to the 'lizard-hipped' dinosaurs (the saurischians). Being herbivores that sometimes lived in herds, they were more numerous than the saurischians. Many were prey animals for the theropods and were usually smaller than the sauropods.



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