DINOSAURS - Weird Creatures

Dinosaurs first appeared about 230 million years ago. They ruled the Earth for about 135 million years until an extinction event 65 million years ago wiped out all but bird-like dinosaurs. Scientists don't agree entirely on what happened, but the extinction likely was a double or triple whammy involving an asteroid impact, choking chemicals from erupting volcanoes, climate change and possibly other factors. Yet only the big, classic dinosaurs are extinct. Birds are living dinosaurs, most experts believe.