Tooth crown form as an indicator of niche partitioning among Late Miocene/Early Pliocene hyenas from ‘E’ Quarry, Langebaanweg, South Africa
Abstract The late Miocene/early Pliocene ‘E’ Quarry deposits at Langebaanweg, South Africa, have yielded fossil material of at least four hyena species ( Ikelohyaena abronia , Hyaenictitherium namaquensis , Chasmaporthetes australis , Hyaenictis hendeyi ). The co-occurrence of four closely-related hyaenids at Langebaanweg raises interesting questions about niche partitioning that have not been sufficiently addressed. In the only previous systematic attempt to tackle this issue, an analysis of m1 lengths, m1 trigonid lengths and p3 widths found evidence for community-wide character displacement in the first two variables. Here, a geometric morphometric approach is used to compare p2, p3, p4 and m1 (carnassial) crown form to better understand feeding niche partitioning among these four hyena species. While results indicate that all four species are very similar in crown shape, I. abronia and H. namaquensis tend to have slightly shorter, broader cheek teeth than C. australis and H. hendeyi . This suggests that I. abronia and H. namaquensis may have been less carnivorous than C. australis and H. hendeyi . The biggest difference between the species however relates to crown size. The four species exhibit community-wide character displacement with respect to p3 and p2 crown size, but not p4 crown size. While box plots based on crown log centroid size suggest that these hyenas also exhibit community-wide character displacement with respect to m1 crown size, this could not be statistically tested due to small sample size. These results support a previous suggestion that community-wide character displacement was in operation among the ‘E’ Quarry hyenas and probably played a major role in niche partitioning and in reducing inter-specific competition.