Primitive mammals. Artwork of various mammal species that existed during the Paleocene and Eocene epochs (between 65 and 33.7 million years ago). The three small mammals at lower left are, clockwise from bottom left: Ptilodus, Chiracus and Plesiadapis. The large browsing mammals across centre are, from left: Coryphodon, Eobasileus and a large type of early rhino (Family Rhinocerotidae). The horse-like mammals drinking from the pool are a pair of Hyracotherium.