The Paleocene, lasting from about 66 to 56 million years ago, is the first epoch of the Paleogene period of the Cenozoic era. It began after the catastrophic extinction event at the end of the Cretaceous period.
The Paleocene was a time of rapid recovery and rebuilding after the dinosaurs disappeared. The climate was warm and humid, with no polar ice caps. Mammals began to rapidly diversify and grow in size. Early primates evolved in the jungles, while giant reptiles like the 40-foot-long snake Titanoboa ruled the swamps. This epoch concluded with a massive global warming event called the PETM (Paleocene-Eocene Thermal Maximum), which triggered mass migrations and the evolution of many modern mammal groups.