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Ancestrally, dinosaurs showed approximately 50 caudal vertebrae, although their number, size, and shape varied considerably in the separate groups. The number of caudals decreased along the evolutionary line leading to modern birds; in the latter, the remaining caudals are fused together into a pygostyle.
tr This is a list of stratigraphic units from which dinosaur body fossils have been recovered. Although Dinosauria is a clade which includes modern birds, this article covers only Mesozoic stratigraphic units. Units listed are all either formation rank or higher (e.g. group).
The following outline is provided as an overview of and topical guide to dinosaurs: . Dinosaurs – diverse group of animals of the clade and superorder Dinosauria.They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period (about in 1963) until the end of the Cretaceous (2000), when the Cretaceous–Paleogene extinction event led to the extinction ...
Dinosaurs belong to a group known as archosaurs, which also includes modern crocodilians. Within the archosaur group, dinosaurs are differentiated most noticeably by their gait. Dinosaur legs extend directly beneath the body, whereas the legs of lizards and crocodilians sprawl out to either side. [26]
Dinosaur classification began in 1842 when Sir Richard Owen placed Iguanodon, Megalosaurus, and Hylaeosaurus in "a distinct tribe or suborder of Saurian Reptiles, for which I would propose the name of Dinosauria." [1] In 1887 and 1888 Harry Seeley divided dinosaurs into the two orders Saurischia and Ornithischia, based on their hip structure. [2]
The saurischian hip structure led Seeley to name them "lizard-hipped" dinosaurs, because they retained the ancestral hip anatomy also found in modern lizards and other reptiles. He named ornithischians "bird-hipped" dinosaurs because their hip arrangement was superficially similar to that of birds, though he did not propose any specific ...
This category is for pages relating to dinosaur anatomy, such as physical features or parts. For anatomic features which are not possessed solely by dinosaurian groups, (such as the Triceratops neck frill which is also employed by the Frill-necked Lizard ), they may be included if it is fairly evident or common in dinosaur anatomy overall.
Diplodocus is among the most easily identifiable dinosaurs, with its typical sauropod shape, long neck and tail, and four sturdy legs. For many years, it was the longest dinosaur known. For many years, it was the longest dinosaur known.