Paleogene Period

The Paleogene period marked a significant transition following the extinction of the dinosaurs, witnessing the rapid diversification of mammals and birds.

With dinosaurs gone, mammals filled their vacant ecological niches with remarkable speed. Many modern mammal orders emerged during this time, including early primates (lemur-like forms), ancestors of carnivores (cats and dogs), early horses and relatives, and the first whales—which evolved from land-dwelling ancestors in one of evolution's great transformations.

The early Paleogene was characterized by a very warm global climate, with dense forests covering much of the planet and tropical conditions extending to high latitudes. A gradual cooling trend began later, with Antarctica starting to glaciate and grasslands beginning to spread.

Birds also diversified dramatically, filling many ecological roles and occasionally becoming giant predators (terror birds).

The Paleogene was the dawn of the modern world—a time when mammals inherited the Earth.