Phylogenetic, paleodemographic, and taphonomic implications of Victoriapithecus deciduous teeth from Maboko, Kenya

More than 240 milk teeth of Victoriapithecus macinnesi, representing all elements of the deciduous dentition, are described. Their morphology is intermediate between that of hominoids and cercopithecids. Unlike colobine and cercopithecine milk teeth, Victoriapithecus dp3s, dp4s, and at least 7 (14%) dp4s lack transverse distal loph(id)s and are not bilophodont. Victoriapithecus also differs from cercopithecids in having less elongated deciduous premolars, a dp3 metacone set mesial to a very small hypocone, a dp4 crista obliqua, and a dp4 hypoconulid. The deciduous canines and incisors of Victoriapithecus are like those of other cercopithecids in having an uneven distribution of enamel around a compressed (rather than cylindrical) root, but differ from cercopithecids and resemble hominoids in being more elongated. Since Colobinae and Cercopithecinae share features of the deciduous dentition that are derived relative to Victoriapithecus and hominoids, extant Old World monkeys are interpreted as representing the sister-taxon of the middle Miocene cercopithecoids. Due to a dramatic increase in the number of deciduous teeth found at Maboko Island, juvenile individuals represent a much larger proportion of recently excavated Victoriapithecus collections than is true of pre-1987 assemblages which mainly derive from sediment first excavated during the 1930s and 1940s. Age distribution differences between pre- and post-1987 samples indicate that paleontological collection procedures were more important than taphonomic biases in determining the paleodemographic profile of the Maboko fossils. Since the Victoriapithecus assemblage from Maboko is strikingly similar to that of fossil Theropithecus oswaldi from Olorgesailie in terms of the large number of specimens and high representation of juvenile and infant individuals, the latter can no longer be viewed as unique among cercopithecoid fossil assemblages. Rather than being related to a specific cause of death, such as selective hunting of T. oswaldi by Homo (Shipman et al. [1981] Curr. Anthropol. 22:257-268), the large number of cercopithecoids at both sites is attributed to the fact that both assemblages represent excavated samples and that the preferred habitats of the extinct monkeys were probably at or near the site of deposition. The greater number of young adult male than female canines in the apparently attritional Maboko Bed 5 assemblage, indicate that the social organization of V. macinnesi may have been similar to that of modern macaques, with males migrating out of their natal group and suffering higher death rates than females at puberty.