User:Dinoguy2/Test/Dinosaur
From Wikipedia, the free encyclopedia
Dinosaurs are a diverse group of animals that included the dominant terrestrial vertebrates of the Mesozoic era. The sole surviving group, the birds, continue to represent the most abundant group of vertebrates on land. Dinosaurs appeared during the late Triassic period (about 230 million years ago), and many major lineages, including the major extinct groups such as the long-necked sauropods, herbivorous ornithischians, and several groups of bird-like theropods, attained large to gigantic sizes during the Jurassic and Cretaceous periods. At the end of the Cretaceous (65.5 million years ago), the Cretaceous–Paleogene extinction event led to the extinction all the large forms. While many types of bird also became extinct at the end of the Cretaceous along with all other dinosaur groups, some groups survived to become the ancestors of all modern birds.[1]
Dinosaurs | |
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Mounted skeletons of Allosaurus fragilis (left) and Stegosaurus stenops (right), Denver Museum of Nature and Science | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dracohors |
Clade: | Dinosauria Owen, 1842 |
Dinosaurs are a diverse and varied group of animals. Of (extinct) non-avian dinosaurs Paleontologists have identified over 500 distinct genera in the extinct groups[2] and more than 1,000 different species;[3] modern birds, at over 9,000 species, are the most diverse group of vertebrate besides perciform fish.[4] Dinosaurs are represented on every continent by both extant species and fossil remains.[5] Some dinosaurs are herbivorous, others carnivorous. Many dinosaurs, including birds, have been bipedal, though many extinct groups were quadrupedal, and some were apparently able to shift between these body postures. Dinosaurs are often noted for their elaborate visual display structures; many species possess crests made up of bone, keratin, and feathers, and some Mesozoic groups developed even more elaborate skeletal modifications such as horns, spikes and other armor. Dinosaurs were the dominant terrestrial herbivores and carnivores for most of the Mesozoic, and have been the planet's dominant flying vertebrate since the extinction of the pterosaurs. All known dinosaurs living and extinct lay eggs, and with the exception of some derived birds (e.g., some penguins) build nests.
Since the first dinosaur fossils were recognized in the early 19th century, mounted fossil dinosaur skeletons or replicas have been major attractions at museums around the world, and dinosaurs have become a part of world culture. They have been featured in best-selling books and films such as Jurassic Park, and new discoveries are regularly covered by the media. In informal speech, the word "dinosaur" is used to describe things that are impractically large, obsolete, or bound for extinction,[6] reflecting the outdated view that dinosaurs were maladapted monsters of the ancient world.[citation needed]