The poles are free of ice. Dinosaurs and other large reptiles peak as the dominant vertebrate life form on Earth. Dinosaurs extend their range throughout every continent. Horned dinosaurs are common, as are armored ankylosaurs and spiky nodosaurs . In the shallow seas, invertebrates live in great diversity.
Ammonites are a dominant group.
Gastropods , corals, sea urchins flourish. Extinctions also occur among ammonites, corals, and other invertebrates. Age of Mammals. Paleocene, Eocene, Oligocene, Miocene, and Pliocene Epochs. During the Paleocene, the vast inland seas of the Cretaceous Period dry up, exposing large land areas in North America and Eurasia.