The cenozoic era began at about 65 million years ago, and it lasted until about 2 million years ago. During this era, the great ice-age began. Glaciers were everywhere accros the land. People were starting to develop, and there were a lot of mammals too. There were the ancestors of the horse, and rhinoceros roaming in Europe and North America. There were large mammals, the ancestors of the elephants, and they were called mamkoths.