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Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomic , morphological and ecological standpoints.
The physiology of dinosaurs has historically been a controversial subject, particularly their thermoregulation.Recently, many new lines of evidence have been brought to bear on dinosaur physiology generally, including not only metabolic systems and thermoregulation, but on respiratory and cardiovascular systems as well.
Examining fossils of non-avian dinosaurs in search of sexually dimorphic characteristics requires the supply of complete and articulated skeletal and tissue remains. As terrestrial organisms, dinosaur carcasses are subject to ecological and geographical influence that inevitably constitutes the degree of preservation.
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 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 are unique in showing a perforate or open acetabulum, where the full extent of the socket is a hole without infilling bone. [1] acromion The acromion is a bony ridge on the outer distal end of the scapula that functions in providing an attachment for the clavicle.
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All carnivorous dinosaurs (certain types of theropods) are traditionally classified as saurischians, as are all of the birds and one of the two primary lineages of herbivorous dinosaurs, the sauropodomorphs. At the end of the Cretaceous Period, all saurischians except birds became extinct in the course of the Cretaceous–Paleogene extinction ...