Dinosaurs

Dinosaurs (meaning "terrible lizards") are a varied group of 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 their are still frequent new discovery.

Dinosaurs appeare in the Upper Triassic, about 230 million years ago. 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 from the earliest theropods during the late Jurassic. And so they were the only line of dinosaurs to survive to the present day.

Dinosaurs had adaptations which helped make them success. 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. Most of the smaller dinosaurs had feathers, and were probably warm-blooded. This would make them active, with a higher metabolism than modern reptiles. Social interaction, with living in herds and co-operation seems very likely for some types.