Oreopithecus (Greek for "mountain ape"); pronounced ORE-ee-oh-pith-ECK-us
Islands of southern Europe
Late Miocene (10-5 million years ago)
Size and Weight:
About four feet tall and 50-75 pounds
Plants, nuts and fruit
Longer arms than legs; monkey-like feet
Most of the prehistoric primates that preceded modern humans led lives that were nasty, brutish and short, but this doesn't appear to have been the case with Oreopithecus--because this chimpanzee-like mammal had the good fortune to live on isolated islands off the Italian coast, where it was relatively free from predation. A good clue to the comparatively trouble-free existence of Oreopithecus is that paleontologists have unearthed about 50 complete skeletons, making this one of the best understood of all ancient apes.
As so often happens with animals restricted to island habitats, Oreopithecus possessed a strange mix of features, including strong, gripping, monkey-like feet, an ape-like head with teeth reminiscent of the earliest humans, and (last but not least) longer arms than legs, a clue that this primate spent much of its time swinging from branch to branch. (There's also some tantalizing evidence that Oreopithecus may have been able to walk upright for short periods of time, which has thrown a wrench into the usual timelines for hominid evolution.) Oreopithecus met its doom when plunging sea levels connected its islands with the mainland, whence its ecosystem was invaded by the mammalian megafauna of continental Europe.
By the way, the name Oreopithecus has nothing to do with the famous cookie; "oreo" is the Greek root for "mountain" or "hill," though this hasn't prevented some paleontologists from affectionately referencing Oreopithecus as the "cookie monster."