Feeding ecology of Tragelaphini (Bovidae) from the Shungura Formation, Omo Valley, Ethiopia: Contribution of dental wear analyses

Abstract

To better understand the environmental conditions that prevailed in the Plio-Pleistocene Shungura Formation, Lower Omo Valley, Ethiopia, we analyze the feeding preferences of Tragelaphini, the third most common tribe of Shungura bovids. Molar mesowear and dental microwear texture analyses were applied to three species (Tragelaphus rastafari, T. nakuae, and T. gaudryi) and body mass estimates were calculated for the T. rastafari-nakuae lineage to test whether dietary shifts were linked to body mass changes. We compare our results with previous work on stable carbon isotopes (δ13C) of enamel, which indicated that tragelaphins from the Shungura Formation possessed dietary flexibility. We found that the both the T. rastafari-nakuae lineage and T. gaudryi maintained a mixed feeding dietary niche, with varying proportions of C3 versus C4 inputs, from ~3.6 to >2 Ma. Our results show that T. rastafari consumed more browse than its descendant, T. nakuae, which was a mixed feeder consuming a greater proportion of C4 dicots ~ 2.8 Ma. The T. rastafari-T. nakuae dietary shift may reflect environmental changes in the Shungura Formation during this time, but appears to be offset from body mass increases in this lineage, which occurred gradually through the Plio-Pleistocene. This study highlights the importance of a multi-proxy approach to precisely determine the dietary ecologies of extinct bovids and points to how each proxy offers a slightly different perspective on the ecology of fossil organisms.