TRIASSIC

The first dinosaurs appeared The Earth looked much different at the beginning of the Triassic period than it does today, as all of the land was massed in one super continent called Pangaea. The climate was hot and dry. Mammal-Like Reptiles dominated the land and some of them grew to lengths of almost 20 feet. The first dinosaurs also appeared during this time and these included the dog-sized meat-eaters Eoraptor ("the dawn reptile") and Hererrasaurus. In the late Triassic period prosauropods, 20-foot-long plant-eaters, also emerged. They had small heads and were able to walk on two or four legs.

A massive extinction paved the way for dinosaurs The greatest known extinction event in Earth's history occurred at the beginning of the Triassic. This event paved the way for dinosaurs to supplant Mammal-Like Reptiles as the most dominant creatures on the planet. While not all of the Mammal-Like Reptiles vanished, they became vulnerable to the emerging dinosaurs. Many scientists believe that as the dinosaurs got bigger, faster and more ferocious, they killed most of the Mammal-Like Reptiles, and those that survived were the smallest of these creatures. Eventually, the only ones left were the very smallest and these evolved into early mouse-sized mammals.

Dinosaurs begin to grow and diversify The plant-eating dinosaurs, which appeared during the mid-to-late Triassic more than 200 million years ago, were the first ornithischians, or bird-hipped dinosaurs, and were no bigger than turkeys. Huge ferns and other primitive non-flowering trees dominated the land. Grass never grew during the Triassic and the dinosaurs got bigger and bigger as a result of having little competition from any other forms of life on the land. One of the most significant developments to occur during the latter part of the Triassic was that some creatures took to the air. Two families of animals began to develop at this time - flying reptiles, or Pterosaurs, and the first members of the family that became birds.