Definition
Triceratops horridus skeleton, American Museum of Natural HistoryUnder phylogenetic taxonomy, dinosaurs are usually defined as the group consisting of "Triceratops, Neornithes [modern birds], their most recent common ancestor, and all descendants".[10] It has also been suggested that Dinosauria be defined with respect to the most recent common ancestor of Megalosaurus and Iguanodon, because these were two of the three genera cited by Richard Owen when he recognized the Dinosauria.[11] Both definitions result in the same set of animals being defined as dinosaurs: "Dinosauria = Ornithischia + Saurischia", encompassing theropods (mostly bipedal carnivores and birds), ankylosaurians (armored herbivorous quadrupeds), stegosaurians (plated herbivorous quadrupeds), ceratopsians (herbivorous quadrupeds with horns and frills), ornithopods (bipedal or quadrupedal herbivores including "duck-bills"), and, perhaps, sauropodomorphs (mostly large herbivorous quadrupeds with long necks and tails).
الرئيسية 
