Size and Weight:
One of the first prehistoric primates ever to be identified--naturalists were studying its fossilized teeth as far back as the early 19th century--Pliopithecus is also one of the least well understood (as can be inferred from its name--this "Pliocene ape" actually lived in the earlier Miocene epoch). Pliopithecus was once thought to be directly ancestral to modern gibbons, and hence one of the earliest true apes, but the discovery of the even earlier Propliopithecus ("before Pliopithecus") has rendered that theory moot. Further complicating matters, Pliopithecus was only one of more than two dozen similar-looking apes of Miocene Eurasia, and it's far from clear how they were all related to each other.
Thanks to later fossil discoveries from the 1960's, we know a lot more about Pliopithecus than the shape of its jaws and teeth. This prehistoric ape possessed very long, equally sized arms and legs, which makes it unclear whether it "brachiated" (i.e., swung from branch to branch), and its large eyes didn't quite face fully forward, casting doubts on the extent of its stereoscopic vision. We do know (thanks to those ubiquitous teeth) that Pliopithecus was a relatively gentle herbivore, subsisting on the leaves of its favorite trees and probably spurning the occasional insects and small animals enjoyed by its omnivorous relatives.