Twenty-eight separate species of rabbits are found on all continents except Antarctica. They were introduced to Australia, but are native elsewhere. Rabbits have appeared in the fossil record for at least 40 million years, dating back to the Eocene Epoch, a period of time which takes its name from the Greek word for dawn. The name fits, for the Eocene saw a new dawn for many modern species, including mammals, a kingdom of which rabbits are a member. Older versions were slightly larger, as was the case with many mammals, but rabbit anatomy has undergone very little change. The earliest fossils reveal bodies built for speed and large ears to detect predators, features that are still prominent in modern rabbits.