Observed diversity among bear species occurred late in the Miocene, the major exception being the Giant Panda at the beginning of the Miocene. The family Ursidae is nonetheless monophyletic, with the Giant Panda as the sister group (outgroup) to the remaining species. Divergence within the family Procyonidae is even older, dating to the mid Oligocene. Morphological similarities between Lesser and Giant Pandas are the result of convergence.