When the dinosaurs lived, the Earth's continents were jammed together into a supercontinent called Pangaea and the Earth was warmer than it is now. The dinosaurs went extinct 65 million years ago, probably because of the environmental changes brought about by an asteroid hitting the Earth. The dinosaurs went extinct about 65 million years ago, at the end of the Cretaceous period , which was a time of high volcanic and tectonic activity . There are a lot of theories why the extinction occurred. The most widely accepted theory is that an asteroid impact caused major climactic changes to which the dinosaurs couldn't adapt.
Dinosaurs probably live on today as the birds .
All that's left of the dinosaurs are fossils and, perhaps,the birds. Some dinosaurs were very bird-like and may be the ancestors of today's birds. There are almost 500 described dinosaur genera and many more species. The only three dinosaurs known at the time were Megalosaurus , Iguanodon , and Hylaeosaurus , very large dinosaurs. The oldest known dinosaur is Eoraptor , a meat-eater from about 228 million years ago.