Around 30 mammal orders existed by the end of the Paleocene epoch, twice as many prior to the K–Pg extinction event. Within 10 million years of the passing of the dinosaurs, after petm, all 18 modern mammal orders existed.
Recovery from petm was relatively quick: 120,000 to 170,000 years. A biogeochemical feedback system engendered carbon burial and a rapid reversal of the warming.
~40 MYA mouse-sized primates migrated from Asia into Africa. There they found lush conditions with few carnivores, prompting a burst of speciation; whence arose anthropoids: the clade from which humans descended.