Dinosaur
clade of sauropsid vertebrates that dominated the Mesozoic Era (including birds) / From Wikipedia, the free encyclopedia
Dinosaurs are a group of Archosaur reptiles of the clade Dinosauria.[1] Dinosaurs eventually gave rise to birds.
Dinosaur | |
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A collection of fossil dinosaur skeletons. Clockwise from top left: Microraptor gui (a winged theropod), Apatosaurus louisae (a giant sauropod), Edmontosaurus regalis (a duck-billed ornithopod), Triceratops horridus (a horned ceratopsian), Stegosaurus stenops (a plated stegosaur), Pinacosaurus grangeri (an armored ankylosaur) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dracohors |
Clade: | Dinosauria Owen, 1842 |
Major groups | |
Dinosaurs were the most powerful land animals of the Mesozoic era. Over 500 different genera of dinosaurs are known.[2] Fossils of dinosaurs have been found on every continent.
Dinosaurs began in the Upper Triassic, about 230 million years ago (mya).[3] The earliest date of a dinosaur fossil is that of Eoraptor and Herrerasaurus from Argentina, and Saturnalia from Brazil, 237 to 228 mya.[4]
By the early Jurassic they were the top land vertebrates, and dominated most environments on land. They continued until the K/T extinction event 66 million years ago.[5]
From the fossil record, it is known that birds are living feathered dinosaurs.[6] They evolved from earlier theropods during the later Jurassic.[7] They were the only line of dinosaurs to survive to the present day.[8]
Dinosaurs had adaptations that helped make them successful. The first known dinosaurs were small predators that walked on two legs.[9][10] All their descendants had an upright posture, with the legs underneath the body. This transformed their whole life-style. There were other features. Most of the smaller dinosaurs had feathers, and were probably warm-blooded. This would make them active, with a higher metabolism than modern reptiles. Social interaction, with living in herds and co-operation, seems certain for some types. The existence of communal egg-laying sites is best understood if the adults travelled in herds, as herbivores do today.
The first fossils were recognised as dinosaurs in the early 19th century. Some of their bones were found much earlier, but were not understood. William Buckland, Gideon Mantell and Richard Owen saw these bones were a special group of animals. Georges Cuvier was also important in explaining what dinosaurs were. Dinosaurs are now major attractions at museums around the world. They have become part of popular culture. There have been best-sellng books and movies. New discoveries are reported in the media.