Dietary characterization of the hominoid Khoratpithecus (Miocene of Thailand): evidence from dental topographic and microwear texture analyses

Abstract

The genus Khoratpithecus, a hominoid thought to be related to the orangutan lineage, is represented by two known fossil species K. chiangmuanensis and K. piriyai. Both were discovered in Southeast Asia (Thailand) and are dated to the Middle and Late Miocene, respectively. In this study, dental topographic and microwear texture analyses were used to examine molars from both of these species, with the goal of understanding their dietary preferences. Although sample sizes are small for Khoratpithecus, available data are compared to that collected for extant apes. Environmental evidence, such as botanical remains and sedimentological data, is also considered for comparisons with dietary reconstruction. Results from dental topographic analysis suggest that the two fossil species were better adapted to a diet of fruits than to one of leaves, much like the living orangutan or chimpanzee. Results from microwear texture analysis further support this, suggesting that Khoratpithecus preferred soft fruits to hard fruits or seeds. And finally, the botanical and sedimentological evidence point to environments for Khoratpithecus that would have been compatible with a fruit-eating species. Given the small sample sizes available for analysis, however, definitive judgments are not yet possible at this time.

Dental topography and diets of four old world monkey species

“…Occlusal slope and relief also tend to vary according to diet. Gorillas have higher occlusal slopes and relief values than do chimpanzees at given stages of wear, and orangutans are predictably between the other two [Merceron et al, 2006;Ungar, 2007;]. This corresponds to reported differences in the diets of these species, and morphological differences remain comparable across wear stages.…”

“…In essence, teeth tend get flatter as they wear down. Colobine and cercopithecine M 2 s examined in this study followed the same trend, as did colobine M 1 s. The cercopithecine M 1 s did not, however, as there was no significant Previous studies of living and fossil hominids also showed no interaction between wear stage and taxon, suggesting that shape differences between species remain consistent through the wear sequence [Merceron et al, 2006;Ungar, 2004Ungar, , 2007. Cercopithecoid M 2 results likewise evinced no significant interactions between wear stage and taxon for any of the variables when considered individually.…”

“…Results from previous studies showed differences in occlusal slope and relief related to broad dietary categories in hominoids [Merceron et al, 2006;Teaford & Ungar, 2006;. Gorillas have higher occlusal slope and relief values than chimpanzees, and orangutans are intermediate at all wear stages.…”

“…Primate dental topographic analyses have thus far been published for large samples of chimpanzee, gorilla, orangutan, howler monkey and sifaka molars [Dennis et al, 2004;King et al, 2005;Merceron et al, 2006;Teaford & Ungar, 2006;Ungar, 2006Ungar, , 2007. These studies indicate that occlusal slope and relief values tend to be lower in more worn specimens, whether one is considering apes, New World monkeys or lemurs.…”

“…This approach uses tools available in geographic information systems (GIS) to characterize surfaces from 3D point clouds representing tooth crowns. Resulting measurements of surface slope, angularity, and relief have all been shown to separate primates with differing diets [Dennis et al, 2004;King et al, 2005;Merceron et al, 2006;Teaford & Ungar, 2006;Ungar, 2006Ungar, , 2007Ungar & Bunn, 2007;.…”