page_title: Dinosaur
section_title: Dinosaur classification
hierarchical_section_title: Dinosaur / Types of dinosaurs / Dinosaur classification
caption_attribution_description: English: Female House Sparrow in New Castle, Delaware
context_page_description: Dinosaurs are a varied group of Archosaur reptiles. They were the dominant land animals of the Mesozoic era. Over 500 different genera of dinosaurs are known. Fossils of dinosaurs have been found on every continent, and there are still frequent new discoveries.
  Dinosaurs appeared in the Upper Triassic, about 230 million years ago. The earliest date of a dinosaur fossil is that of Eoraptor and Herrerasaurus from the Argentine, and Saturnalia from Brazil, 237 to 228 mya. By the early Jurassic they were the top land vertebrates, and dominated most environments on land. They continued until the sudden K/T extinction event 66 million years ago.
  From the fossil record, we know that birds are living feathered dinosaurs. They evolved from the earliest theropods during the Jurassic. They were the only line of dinosaurs to survive to the present day.
  Dinosaurs had adaptations which helped make them successful. The first known dinosaurs were small predators that walked on two legs. All their descendants had an upright posture, with the legs underneath the body. This transformed their whole life-style. There were other features.
context_section_description: The following is a simplified list of dinosaur groups based on their evolution. Groups with a dagger (†) next to them don't have any living members.
  Dinosauria
  Saurischia ("lizard-hipped"; includes Theropoda and Sauropodomorpha)
  Theropoda (all bipedal; most were carnivorous)
  †Herrerasauria (early bipedal carnivores)
  †Coelophysoidea (small, early theropods; includes Coelophysis and its close relatives)
  †Dilophosauridae (early crested and carnivorous theropods)
  †Ceratosauria (generally elaborately horned, the dominant southern carnivores of the Cretaceous)
  Tetanurae (meaning "stiff tails"; includes most theropods)
  †Megalosauroidea (early group of large carnivores including the semiaquatic spinosaurids)
  †Carnosauria (Allosaurus and close relatives, like Carcharodontosaurus)
  Coelurosauria (feathered theropods, with a range of body sizes and niches)
  †Compsognathidae (common early coelurosaurs with smaller legs)
  †Tyrannosauridae (Tyrannosaurus and its close relatives; had smaller legs)
  †Ornithomimosauria (meaning "ostrich-mimics"; mostly toothless; carnivores to possible herbivores)
  †Alvarezsauroidea (small insectivores with short arms that each had one large claw)
  Maniraptora (meaning "hand snatchers"; had long, slender arms and fingers)
  †Therizinosauria (bipedal herbivores with large hand claws and small heads)
  †Oviraptorosauria (mostly toothless; their diet and lifestyle are uncertain)
  †Archaeopterygidae (small, winged theropods or primitive birds)
  †Deinonychosauria (small to medium-sized, bird-like, with a distinctive toe claw.)
  Avialae (modern birds and their extinct relatives)
  †Scansoriopterygidae (small primitive avialans with long third fingers)
  †Omnivoropterygidae (large, early short-tailed avialans)
  †Confuciusornithidae (small toothless avialans)
  †Enantiornithes (primitive flying avialans that lived in trees)
  Euornithes (advanced flying birds)
  †Yanornithiformes (toothed Cretaceous Chinese birds)
  †Hesperornithes (specialized aquatic diving birds)
  Aves (modern, beaked birds and their extinct relatives)
  †Sauropodomorpha (herbivores with small heads, long necks, long tails)
  †Guaibasauridae (small, primitive, omnivorous sauropodomorphs)
  †Plateosauridae (primitive, bipedal "prosauropods")
  †Riojasauridae (small, primitive sauropodomorphs)
  †Massospondylidae (small, primitive sauropodomorphs)
  †Sauropoda (very large and heavy, usually over 15 m (49 ft) long; quadrupedal)
  †Vulcanodontidae (primitive sauropods with pillar-like arms and legs)
  †Eusauropoda ("true sauropods")
  †Cetiosauridae ("whale reptiles")
  †Turiasauria (European group of Jurassic and Cretaceous sauropods)
  †Neosauropoda ("new sauropods")
  †Diplodocoidea (skulls and tails elongated; teeth typically narrow and pencil-like)
  †Macronaria (boxy skulls; spoon- or pencil-shaped teeth)
  †Brachiosauridae (long-necked, long-armed macronarians)
  †Titanosauria (diverse; stocky, with wide hips; most common in the late Cretaceous of southern continents)
  †Ornithischia ("bird-hipped"; diverse bipedal and quadrupedal herbivores)
  †Heterodontosauridae (small basal ornithopod herbivores/omnivores with prominent canine-like teeth)
  †Thyreophora (armored dinosaurs; mostly quadrupeds)
  †Ankylosauria (scutes as primary armor; some had club-like tails)
  †Stegosauria (spikes and plates as primary armor)
  †Neornithischia ("new ornithischians")
  †Ornithopoda (various sizes; bipeds and quadrupeds; evolved a method of chewing using flexible skulls and many teeth)
  †Marginocephalia (Had dome-like growths on their skulls made of bone)
  †Pachycephalosauria (bipedal with domed or knobby growth on skulls)
  †Ceratopsia (quadrupeds with frills; many also had horns)
caption: The house sparrow is one of the most common living theropods
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