Eocene 58-37 mya Mammals abound. Primitive whales appear . Paleocene 65-58 mya First large mammals and primitive primates, plesiadapiforms . 98- 65 mya High tectonic and volcanic activity. Primitive marsupials develop.
Continents have a modern-day look.
Minor extinction 82 mya. Lower 146-98 mya The heyday of the dinosaurs. The first crocodilians, and feathered dinosaurs appear. Minor extinctions at 144 and 120 mya. Jurassic Period 208 to 146 mya Many dinosaurs, including the giant Sauropods .