Around 230 million years ago the first dinosaur fossils started to be found in places such as South America, Madagascar and Europe. These dinosaurs were much smaller than their later descendents and can be divided into two groups: The prosauropod dinosaurs, which are the primitive vegetarian forerunners of sauropods such as Diplodocus, and the more common coelurosaurs which were two-legged meat-eaters that would later evolve into giants such as Tyrannosaurus and Allosaurus.
The Triassic coelurosaur dinosaurs were small, nimble and built to survive in the harsh Triassic landscape. Unlike many of the four-legged lumbering reptiles around them, the coelurosaurs could use their two legs to travel at speed and to manoeuvre themselves out of dangerous situations. Their light skulls, long snout and flexible necks were ideal for hunting small animals such as insects, amphibians and other reptiles but the coelurosaurs could also live by scavenging when times were hard.
The arrival of the coelurosaur dinosaurs was a landmark in evolution. They quickly evolved into newer and larger species and spread themselves around the globe until, by the start of the Jurassic period, the dinosaurs dominated the land. The coelurosaurs helped found a dynasty that produced the largest and most feared land predators of all time. After the giant extinction event of 65 million years ago the only Earthly legacy of the dinosaurs are the birds which split from the coelurosaur dinosaurs sometime during the Late Jurassic period.