Enigmatic Anthropoid or Misunderstood Ape?

Abstract

The phylogenetic status of Oreopithecus bambolii from the late Miocene of Italy has been a source of much debate since the species was first described in 1872. This observation in itself is hardly surprising, since most fossil primates known since the end of the last century have acquired a complicated history of ideas on their taxonomic and phylogenetic placement. What is so unusual about Oreopithecus,however, is that this debate has continued to the present,

This chapter is dedicated to the memory of Johannes Hürzeler (1908–1995) whose profoundly important contribution to the study of Oreopithecus and the Baccinello faunas has influenced both of us to follow the same path. The “keeper of the abominable coalman” may no longer be with us, but his remarkable discoveries will undoubtedly continue to inspire and excite the imagination of future generations of vertebrate paleontologists.

and there are no indications from the current literature that its phylogenetic status is close to being resolved (e.g., Delson, 1988; Harrison, 1991; Andrews, 1992; Begun, 1994). The problem is especially perplexing because Oreopithecus is one of the best-known fossil primates. It is easy to comprehend how researchers might have difficulties establishing the relationships of fossil taxa based on one or two isolated teeth or just a few jaw fragments, but Oreopithecus is known from an almost complete subadult skeleton, several partial skeletons, and dozens of relatively complete mandibles and crania. We find ourselves, therefore, in the uncomfortable position of not being able to rely on the excuse favored by most paleontologists in this situation, that the solution to the problem lies in finding more and better material. In the case of Oreopithecus we have all the material we need; the shortcomings are not in the available evidence, but in the way that we view it. So why is it that several generations of primate paleontologists have failed to agree on the evolutionary status of Oreopithecus? A review of the literature clearly shows that part of the problem is as much sociological as it is scientific, involving a complex interplay of different philosophies, politics, and personalities that are difficult to tease apart from the purely empirical evidence. The consequence of these and other contributing factors is that Oreopithecus is perceived to be an “enigmatic anthropoid” (Delson, 1987), one that does not readily conform to our expectations of extinct hominioids based on other lines of evidence. However, is it really that Oreopithecus represents a piece of the puzzle that does not fit, or is it simply because the limitations that we impose on our expectations of hominoid evolution are too narrow, and that Oreopithecus is being made to fit the wrong puzzle altogether? We suspect that it is the latter that represents the crux of the Oreopithecus problem. Of the various factors that have served to confound recent attempts to resolve the phylogenetic relations of Oreopithecus, three can be identified that we believe have had a particularly profound impact.