Hard time classifying fossils due to: fossils indiv vary. Sexual dimorphism diff in b/w sexes if no pelvis could not differ male or female. End of cretaceous period have separation of continents. Move to arboreal life (life in trees) Place of origin of 1st primate unknown but we looking at beginnings by 60 mya. Move for better way to move thru trees. Need for stereoscopic vision (3d vision) grasping hand/foot. 3d vision and grasping, nails over claws, better for hunting insects. Cretecoius, terteiary extinction event (kt, not ct) wtf Allow for adaptive radiation of mammals- due to more niches to fill from 65 to 55 mya. Some primates w/ some features of modern prosimeons. Monkeys and diff kinds of apes appearing. Earliest primates did appear most was contested. Called plesiadaptiformes found in europe and na. And long arms suited for tree life. A bit contested some say earliest primates were missing lot of picture in between.