Dinosaur

Dinosaurs are a diverse group of <a href="/facts/Reptile/04n1uKf1">reptiles</a> of the <a href="/facts/Clade/XefyYmWn">clade</a> Dinosauria. They first appeared during the <a href="/facts/Triassic/r6CNxKXC">Triassic</a> <a href="/facts/Geological_period/6LBR11yQ">period</a>, between 243 and 233.23 <a href="/facts/Million_years_ago/DXcnXuAw">million years ago</a> (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research. They became the dominant terrestrial <a href="/facts/Vertebrate/tT54FSTT">vertebrates</a> after the <a href="/facts/Triassic%25E2%2580%2593Jurassic_extinction_event/5XKTUdt6">Triassic–Jurassic extinction event</a> 201.3 mya and their dominance continued throughout the <a href="/facts/Jurassic/o5Cy4KzX">Jurassic</a> and <a href="/facts/Cretaceous/nwKtFtKx">Cretaceous</a> periods. The <a href="/facts/Fossil/by7NzIA1">fossil</a> record shows that <a href="/facts/Bird/RJF6zwLP">birds</a> are <a href="/facts/Feathered_dinosaur/epRs4crz">feathered dinosaurs</a>, <a href="/facts/Evolution_of_birds/JH4DT1rw">having evolved</a> from earlier <a href="/facts/Theropoda/KUzy1Ef7">theropods</a> during the <a href="/facts/Late_Jurassic/NzU9rlnL">Late Jurassic</a> <a href="/facts/Epoch/ow9RnUFC">epoch</a>, and are the only dinosaur lineage known to have survived the <a href="/facts/Cretaceous%25E2%2580%2593Paleogene_extinction_event/HNyDuEcx">Cretaceous–Paleogene extinction event</a> approximately 66 mya. 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 <a href="/facts/Taxonomy_(biology)/Qkg8wuyw">taxonomic</a>, <a href="/facts/Morphology_(biology)/Nl3B0myy">morphological</a> and <a href="/facts/Ecological/YE8upuJU">ecological</a> standpoints. <a href="/facts/Bird/RJF6zwLP">Birds</a>, at over 11,000 living <a href="/facts/Species/oDg6b96r">species</a>, are among the most diverse groups of vertebrates. Using fossil evidence, <a href="/facts/Paleontologists/60n5yldd">paleontologists</a> have identified over 900 distinct <a href="/facts/Genera/m8EFjSms">genera</a> and more than 1,000 different species of non-avian dinosaurs. Dinosaurs are represented on every continent by both <a href="/facts/Neontology/YK8uj7qU">extant</a> species (birds) and fossil remains. Through the first half of the 20th century, before birds were recognized as dinosaurs, most of the scientific community believed dinosaurs to have been sluggish and <a href="/facts/Poikilotherm/mqqYSlcq">cold-blooded</a>. Most <a href="/facts/Dinosaur_renaissance/Q3LKBtSW">research conducted since the 1970s</a>, however, has indicated that dinosaurs were active animals with elevated <a href="/facts/Metabolism/WxDrm8k5">metabolisms</a> and numerous adaptations for social interaction. Some were <a href="/facts/Herbivorous/me4YFdQA">herbivorous</a>, others <a href="/facts/Carnivorous/q6h6aSqe">carnivorous</a>. Evidence suggests that all dinosaurs were <a href="/facts/Egg-laying/oSgSIVHY">egg-laying</a>, and that <a href="/facts/Nest/7tq5lt4V">nest</a>-building was a trait shared by many dinosaurs, both avian and non-avian.
While dinosaurs were ancestrally <a href="/facts/Bipedal/tvLMG77t">bipedal</a>, many <a href="/facts/Extinct/24p5NP2q">extinct</a> groups included <a href="/facts/Quadrupedal/KMVYdsYf">quadrupedal</a> 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 <a href="/facts/Skeletal/FXc9Y2lF">skeletal</a> modifications such as <a href="/facts/Armour_(anatomy)/BYvjkjtz">bony armor</a> and <a href="/facts/Spine_(zoology)/JWqp5oJW">spines</a>. 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 <a href="/facts/Sauropoda/8Iqh2yEJ">sauropod</a> dinosaurs are estimated to have reached lengths of 39.7 meters (130 feet) and heights of 18 m (59 ft) and were the largest land animals of all time. The misconception that non-avian dinosaurs were uniformly gigantic is based in part on <a href="/facts/Preservation_bias/x4zxN2Hm">preservation bias</a>, as large, sturdy <a href="/facts/Bone/kwJaR6IQ">bones</a> are more likely to last until they are fossilized. Many dinosaurs were quite small, some measuring about 50 centimeters (20 inches) in length.
The first dinosaur fossils were recognized in the early 19th century, with the name "dinosaur" (meaning "terrible lizard") being coined by Sir <a href="/facts/Richard_Owen/M8H3td41">Richard Owen</a> in 1842 to refer to these "great fossil lizards". Since then, mounted fossil dinosaur skeletons have been major attractions at museums worldwide, and dinosaurs have become <a href="/facts/Cultural_depictions_of_dinosaurs/XwWUBpEr">an enduring part of popular culture</a>. The large sizes of some dinosaurs, as well as their seemingly monstrous and fantastic nature, have ensured their regular appearance in best-selling books and films, such as the <a href="/facts/Jurassic_Park/NURIxpYw">Jurassic Park</a> franchise. Persistent public enthusiasm for the animals has resulted in significant funding for dinosaur science, and new discoveries are regularly covered by the media.

Dinosaur open-in-new

Dinosaur