EXTINCTION

The Triassic started with the greatest known extinction of life in the history of the earth. Many scientists believe that at least 80% of all life on Earth vanished - both plant and animal. Gone from the sea were the Trilobites, which had flourished for hundreds of millions of years, and many other types of sea creatures, such as shellfish. Some life recovered, but the world was changed forever. According to very recent evidence, this extinction was caused by a large comet striking the Earth, probably somewhere in the ocean. It is likely that, due to the enormous amount of time that has passed, any evidence of a crater has disappeared due to plate tectonics.

Midway through the Triassic another, less drastic, extinction event occurred. This event allowed dinosaurs to develop and fill in ecological niches that had been vacated because of the extinction. This event did not eliminate the Mammal-Like Reptiles, but it severely decimated their numbers and killed off most of the larger members of this family.