Dinosaur

The dinosaurs were a highly successful group of animals, who got their name from [Sir Richard Owen]?, who proposed the name Dinosauria, meaning 'fearfully great lizard'.

Dinosaurs were descendents of Thecodonts and existed from the middle Triassic to the end of Cretaceous (210-220 to 65 million years ago).

Birds are now generally believed to represent descendents of dinosaurs, and so are classed with them by those who believe groups should be monophyletic.

Other than them, the last dinosaurs disappeared 65 million years ago, most likely caused by the effects a very large meteorite hitting the earth (a theory first proposed by [Walter Alvarez]?).

Classification of dinosaurs

Dinosaurs are divided into two major groups, the Saurischia and the Ornithischia, on the basis of hip structure.

• Saurischia?
  • Theropoda?
    • Ceratosauria? (e.g. Coelophysis?, Procompsognathus?, Dilophosaurus?, Abelisaurus?)
    • Spinosauridae? (e.g. Spinosaurus?)
    • Allosauroidea? (e.g. Allosaurus)
    • Coelurosauria?
      • Tyrannosauroidea? (e.g. Tyrannosaurus rex, Albertosaurus)
      • Ornithomimidae? (e.g. Ornithomimus?, Struthiomimus?, Gallimimums?)
      • Dromaeosauridae? (e.g. Deinonychus?, Velociraptor)
      • Oviraptoridae? (e.g. Oviraptor?)
      • Troodontidae? (e.g. Troodon?)
      • Aves (birds)
  • Sauropodomorpha?
    • Prosauropoda?
    • Sauropoda?
      • Diplodocidae? (e.g. Apatosaurus, Diplodocus, Mamenchisaurus?)
      • Brachiosauridae? (e.g. Brachiosaurus?)
      • Titanosauridae? (e.g. Titanosaurus?, Saltasaurus?)
• Ornithischia?
  • Thyreophora?
    • Stegosauria? (e.g. Stegosaurus?)
    • Ankylosauria? (e.g. Ankylosaurus?, Euplocephalus?, Nodosaurus?)
  • Neornithischia?
    • Ornithopoda? (e.g. Anatosaurus?, Parasaurolophus?, Hypsilophodon?, Iguanodon?)
    • Pachycephalosauria? (e.g. Pachycephalosaurus?)
    • Ceratopsia? (e.g. Triceratops?, Protoceratops?)

Extinction Theories

There are several theories that attempt to explain how and why the dinosaurs became extinct. The one that appears most likely to be true today is that a large meteor? impacted the earth, throwing up a cloud of dust and debris that largely obliterated the Sun and caused mass global extinctions.

/Talk