Warm blooded animals have a high metabolic rate (use up food faster). They can be more active, and for longer, than animals who depend on the environment for heating. Therefore, the idea of warm-blooded dinosaurs insulated by feathers led to the idea that they were more active, intelligent and faster runners than previously thought. [20] Did any terrestrial dinosaurs survive the great extinction event? Yes they did, because we now know that birds are descended from dinosaurs. But dinosaurs as generally understood were eliminated. Several fossils have been found in the Hell Creek Formation about 40,000 years later than the K/T extinction event. Many scientists dismiss the " Paleocene dinosaurs" as re-worked, that is, washed out of their original places and then re-buried in much later sediments. [24] An associated skeleton (e.g. more than one bone from the same individual) found above the K/T boundary would be convincing, but no such finds have been reported. MacLeod, Norman; Rawson, Peter F.; Forey, Peter L.; etal. (1997). "The Cretaceous–Tertiary biotic transition". Journal of the Geological Society. London: Geological Society of London. 154 (2): 265–292. Bibcode: 1997JGSoc.154..265M. doi: 10.1144/gsjgs.154.2.0265. ISSN 0016-7649. S2CID 129654916.

The tallest and heaviest dinosaur known from good skeletons is Giraffatitan brancai (previously classified as a species of Brachiosaurus). Its remains were discovered in Tanzania between 1907 and 1912. Bones from several similar-sized individuals were incorporated into the skeleton now mounted and on display at the Museum für Naturkunde in Berlin; [145] this mount is 12 meters (39ft) tall and 21.8 to 22.5 meters (72 to 74ft) long, [146] [147] and would have belonged to an animal that weighed between 30 000 and 60 000kilograms ( 70 000 and 130 000lb). The longest complete dinosaur is the 27 meters (89ft) long Diplodocus, which was discovered in Wyoming in the United States and displayed in Pittsburgh's Carnegie Museum of Natural History in 1907. [148] The longest dinosaur known from good fossil material is Patagotitan: the skeleton mount in the American Museum of Natural History in New York is 37 meters (121ft) long. The Museo Municipal Carmen Funes in Plaza Huincul, Argentina, has an Argentinosaurus reconstructed skeleton mount that is 39.7 meters (130ft) long. [149] An adult bee hummingbird, the smallest known dinosaur Dinosaurs are a varied group of Archosaur reptiles. [1] Dinosaurs are related to birds and crocodiles. They 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. a b Tennant, Jonathan P.; Chiarenza, Alfio Alessandro; Baron, Matthew (February 19, 2018). "How has our knowledge of dinosaur diversity through geologic time changed through research history?". PeerJ. 6: e4417. doi: 10.7717/peerj.4417. PMC 5822849. PMID 29479504. Padian, Kevin, ed. (1986). The Origin of Birds and the Evolution of Flight. Memoirs of the California Academy of Sciences. Vol.8. San Francisco, CA: California Academy of Sciences. ISBN 978-0-940228-14-6. OCLC 946083441. OL 9826926M.Curry Rogers, Kristina A.; Wilson, Jeffrey A., eds. (2005). The Sauropods: Evolution and Paleobiology. Berkeley: University of California Press. ISBN 978-0-520-24623-2. LCCN 2005010624. OCLC 879179542. Dinosaur bones 'used as medicine' ". BBC News. London: BBC. July 6, 2007. Archived from the original on August 27, 2019 . Retrieved November 4, 2019. Currie, Philip J.; Padian, Kevin, eds. (1997). Encyclopedia of Dinosaurs. San Diego, CA: Academic Press. ISBN 978-0-12-226810-6. LCCN 97023430. OCLC 436848919 . Retrieved October 30, 2019.

The crests and frills of some dinosaurs, like the marginocephalians, theropods and lambeosaurines, may have been too fragile to be used for active defense, and so they were likely used for sexual or aggressive displays, though little is known about dinosaur mating and territorialism. Head wounds from bites suggest that theropods, at least, engaged in active aggressive confrontations. [169] Dinosaurs belong to a group known as archosaurs, which also includes modern crocodilians. Within the archosaur group, dinosaurs are differentiated most noticeably by their gait. Dinosaur legs extend directly beneath the body, whereas the legs of lizards and crocodilians sprawl out to either side. [30] C A saurischian pelvis ( Staurikosaurus) D Lesothosaurus pelvis Dinosaur classification [ change | change source ] Alexander, R. McNeil 2006. Dinosaur biomechanics. Proceedings of the Royal Society B: Biological Sciences. 273 (1596): 1849–1855. [5] (full free access) While dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, and some extinct groups developed skeletal modifications such as bony armor and spines. While the dinosaurs' modern-day surviving avian lineage (birds) are generally small due to the constraints of flight, many prehistoric dinosaurs (non-avian and avian) were large-bodied—the largest sauropod dinosaurs are estimated to have reached lengths of 39.7 meters (130 feet) and heights of 18m (59ft) and were the largest land animals of all time. The misconception that non-avian dinosaurs were uniformly gigantic is based in part on preservation bias, as large, sturdy bones are more likely to last until they are fossilized. Many dinosaurs were quite small, some measuring about 50 centimeters (20 inches) in length.

Discover the world of dinosaurs with our comprehensive list of all known dinosaur species. From the ferocious T-Rex to the majestic Stegosaurus, our list includes over 300 dinosaur names, each with detailed information and images. Marine reptiles, such as ichthyosaurs, plesiosaurs and mosasaurs are not dinosaurs. Nor is Dimetrodon or other reptiles in the same group (previously called 'mammal-like reptiles' and now called synapsids) . Trigger detailed 3D models of selected dinosaurs, including Triceratops, Allosaurus, Stegosaurus and more. View them from every angle with your device, and tap the hotspots on each dino to bring up fact boxes.