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Mounted skeletons of Tyrannosaurus (left) and Apatosaurus (right) at the AMNH. Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago, although the exact origin and timing of the evolution of dinosaurs is the subject of active research.
The following is a simplified classification of dinosaur groups based on their evolutionary relationships, and those of the main dinosaur groups Theropoda, Sauropodomorpha and Ornithischia, compiled by Justin Tweet. [134] Further details and other hypotheses of classification may be found on individual articles. Dinosauria
Early in the period, the modern reptiles, or crown-group reptiles, evolved and split into two main lineages: the Archosauromorpha (forebears of turtles, crocodiles, and dinosaurs) and the Lepidosauromorpha (predecessors of modern lizards and tuataras). Both groups remained lizard-like and relatively small and inconspicuous during the Permian.
List of Asian dinosaurs; List of Australian and Antarctic dinosaurs; List of dinosaurs and other Mesozoic reptiles of New Zealand; List of European dinosaurs; List of Indian and Madagascan dinosaurs; List of North American dinosaurs. List of Appalachian dinosaurs; List of archosaurs of the Chinle Formation; List of dinosaurs of the Morrison ...
Sauropsida (Greek for "lizard faces") is a clade of amniotes, broadly equivalent to the class Reptilia, though typically used in a broader sense to also include extinct stem-group relatives of modern reptiles and birds (which, as theropod dinosaurs, are nested within reptiles as more closely related to crocodilians than to lizards or turtles). [2]
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period , between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research.
Squamata is the largest order of reptiles, comprising lizards, snakes and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,000 species, [15] Approximate world distribution of snakes. Suborder Anguimorpha. Family Anguidae [16]
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]