A micro-CT based study of molar enamel thickness and its distribution pattern in Late Miocene Lufengpithecus lufengensis from Yunnan in Southwestern China

Abstract

ABSTRACT Molar enamel thickness and distribution pattern inform on the functional and dietary adaptation of extant and fossil primates. However, no systematic analysis of enamel thickness has been conducted on Lufengpithecus, a large-bodied fossil hominoid that lived in Southwest China during the late Miocene. In this study, we quantify two-dimensional (2D) enamel thickness and distribution of 68 lightly worn molars of Lufengpithecus (L.) lufengensis using micro-CT scanning data and compare it with modern humans, extant great apes, and fossil hominoids. The results indicate L. lufengensis has relatively thick enamel. It is slightly thicker than extant Pongo and comparable to some thick-enamel fossil pongines, but thinner than modern humans and most fossil hominins. The enamel distribution of L. lufengensis is distinctively unbalanced with relatively more enamel deposited on the cuspal region than the basal region in the molar crown, different from that found in modern humans and extant great apes. Concerning its palaeoecological and functional adaptations, we suggest that the features of thick-enamel and unbalanced distribution pattern in L. lufengensis is related to its adaptation to tough food and broader diets in a seasonal subtropical habitat.