Eocene Epoch, a division of geologic time that began about 54,000,000 years ago and lasted about 17,000,000 years. It is the second epoch of the Tertiary Period. During the Eocene, mammals were the dominant form of animal life. Among them were the ancestors of today's horses, pigs, whales, rats, camels, and monkeys. Reptiles and birds were also common. Plants included elm, maple, beech, and walnut trees.
Archaeology is the study of humanity's material remains -- even a piece of an ancient pot can tell us a lot about the past. But how do archaeologists make sense of these relics?
When it comes to fossils, specimens like Sue the Tyrannosaurus rex grab much of the attention. And while Sue is a staggering 67 million years old, she's a new kid on the block, compared to some of the oldest fossils ever found. What's older than Sue?