Paleogene

The Paleogene Period began 66 million years ago and ended 23.03 million years ago, marking the dawn of the Cenozoic Era. It commenced immediately after the asteroid impact that wiped out the non-avian dinosaurs, leaving a planet full of vacant ecological niches. In this wake, small, surviving mammals rapidly diversified and grew in size, evolving into the ancestors of modern rodents, primates, carnivores, and hoofed herbivores. Birds also diversified into new ecological roles. Earth’s climate during the early Paleogene was exceptionally warm and tropical, allowing dense forests to grow near the polar regions. However, as the continents continued to drift toward their modern positions, Antarctica isolated itself at the South Pole. This tectonic shift altered ocean currents, triggering a long-term global cooling trend that gradually replaced dense forests with more open woodlands by the period's end.