Until 65 million years ago mammals were mostly rat like but once the dinosaurs were gone life started getting more interesting. Once mammals were well established there were a variety of strange mammals that were somewhat like dinosaurs. Whales split off quite early after the dinosaur extinction but they still had elements of pentadactyl limbs and pelvic bones. In the absence of competition from dinosaurs mammals underwent an adaptive radiation in the paleocene and into the eocene. Weather was much warmer then because there was much less coast line. Primates originated in laurasia which was the upper part of pangea that broke off. Flexible five fingered or toes hands and feet. Generalized heterodont dentition and lack of specialized diet. The primate ancestor was insectivorous and probably evolved from a tree-shrew like animal. Adapted to the new angiosperm arboreal habitat especially to the exploitation of resources in the terminal branches.