An ancestor to the primates
There is no doubt that the early insect-eating shrew-like mammals which were the ancestors of such diverse creatures as bats, whales and ant-eaters, also gave rise to the primates. Indeed, an animal like the Tree Shrew (Tupaia glis) could have been an ancestor to the primates. The Tupaia has two characteristics which it shares with the primates; its eye-sockets are completely encircled by bone and its tongue is underlain by a cartilaginous sub-tongue; other insectivores do not possess these characteristics. But the Tree Shrew does not have the other primatehallmarks, namely hands with thumbs that are opposable to the fingers which is required for a true grasping hand, and eyes that face forward with overlapping fields of view so that distances can be judged.
Phylogeny of Primata
Primates include Prosimian ("first apes") and Anthropoid ("man-like") primates, which are further distinguished as "monkeys" (with tails) and "apes" (without tails). The former includes New World (Cebidae) and Old World types (Cercopithecidae). Apes include gibbons (Hylobatidae) and Great Apes (Pongidae and Hominidae, though the latter are now often included in the former family). Molecular and fossil evidence favours separation of the human lineage ca. 4 ~ 5 MYBP, with a chimps rather than gorillas as the closest sister species to humans.
