Craniomandibular variation in the endemic Hispaniolan primate, Antillothrix bernensis

Here we describe new fossil material of Antillothrix bernensis, a Pleistocene-Holocene primate taxon fromHispaniola. It is now represented by seven crania, five mandibles, and dozens of postcranial elementsfrom several paleontologically rich cave systems. The five adult crania included here share a similaroverall profile as well as specific features such as a deep depression at the glabella. The complete anteriordentition of Antillothrix can now be described for the first time; short canine crowns, in the apicobasaldimension, compare well with titi monkeys, but the new crania and mandibles lack the specialized tall-crowned incisors of the extant pitheciids. They do, however, have a diastema between the lateralmaxillary incisors and canines, a feature not present in the previously known crania. The new mandiblesdeepen posteriorly and have a medial inflection of the mandibular ramus, as in some pitheciids, but alsoshare with Xenothrix a significant vertical narrowing of the corpus under P4/M 1 not observed amongextant taxa. Two of the specimens, a cranium and a mandible that do not fit together, exhibit congenitallyabsent third molarsda rarity among extant, noncallitrichine taxa. There is an approximately 1-kg rangein the estimated body mass among the full Antillothrix sample (from 2.4 to 3.4 kg), as well as a range ofapproximately 5 cm 3 of endocranial volume (from 40 to 45 cm 3). With these extended ranges from thenew specimens, Antillothrix can no longer be described as a taxon with a brain size smaller than thatexpected for its body size. Neither of these ranges in the brain size or body size is large enough toindicate a substantial level of sexual dimorphism or to necessitate separating the sample into male andfemale individuals. Given this, and the similar canine sizes for all specimens where they are present, thesample is consistent with a morphologically variable but monomorphic species.