New Craniodental Remains of the Quaternary Jamaican Monkey Xenothrix mcgregori (Xenotrichini, Callicebinae, Pitheciidae), with a Reconsideration of the Aotus Hypothesis1

Abstract

Abstract The Jamaican monkey Xenothrix mcgregori is one of several extinct endemic platyrrhines known from the late Quaternary of the Greater Antilles. Until recently, the hypodigm of Xenothrix was limited to the holotype partial mandible and a handful of tentatively referred postcranial elements. Here we describe several additional fossils attributable to Xenothrix, including the first cranial remains, all of which were recovered in cave deposits in the Jackson's Bay region of southern Jamaica. In addition to a partial face from Lloyd's Cave and a maxillary fragment of a different individual from the same site, the craniodental collection includes two incomplete mandibles with poorly preserved cheekteeth from nearby Skeleton Cave. The new specimens confirm a distinctive derived feature of Xenothrix, i.e., reduced dental formula in both jaws (2/2 1/1 3/3 2/2). Although no examples of the maxillary canine are yet known, its alveolus is notably small. Similarly, although the upper face of Xenothrix is also ...