The EOCENE Epoch is a geological period that lasted from 56 to 33.9 million years ago and was part of the Paleogene Period. It is the second epoch of the Tertiary Period, which is part of the Cenozoic Era. During this time, the Earth's climate was much warmer than it is today, and the first modern mammals appeared. The EOCENE Epoch is considered to be the beginning of the Mammalian Epoch, as it marks the emergence of many modern mammal species.