New insights on feeding habits of Kolpochoerus van Hoepen & van Hoepen, 1932 from the Shungura Formation (Lower Omo Valley, Ethiopia) using dental microwear texture analysis

During the Neogene and the Quaternary, African suids show dental morphological changes considered to reflect adaptations to increasing specialization on graminivorous diets, notably in the genus Kolpochoerus van Hoepen & van Hoepen, 1932. They tend to exhibit elongated third molars and some degree of hypsodonty, suggesting increasing consumption of abrasive grasses. However, the most significant morphological changes are observed more than 1 million years after the increased consumption of C4 plants, such as graminoids. To date, only a few studies have applied dental microwear texture analysis (DMTA) to specimens of Kolpochoerus, which provides information on the mechanical properties of the diet, and therefore bring fundamental insights on the mechanical stresses exerted on dental morphologies. In addition, none has yet focused on specimens from the Shungura Formation (Lower Omo Valley, Ethiopia), which is the most complete Late Pliocene to Early Pleistocene record in eastern Africa. To better interpret the dental microwear textures (DMT) of Kolpochoerus, we built a modern referential using four genera of extant suids with contrasting diets: the herbivores Phacochoerus F.Cuvier, 1826 and Hylochoerus Thomas, 1904, and the omnivores Potamochoerus Gray, 1854 and Sus Linnaeus, 1758. Our results show that their DMT reflect their different feeding habits. In light of these results, we then studied the DMT of 68 Kolpochoerus specimens from the Shungura Formation and dating from about 2.8 Ma to 1.0 Ma. Their DMT differ from extant suids, but some similarities with Phacochoerus are observed. In line with previous studies, we propose that their DMT reflect a high consumption of herbaceous plants (graminoids and non-graminoids), with preferences for young, low-abrasive grasses. Yet, while a high intake of such grasses is consistent with both the shift toward increased C4 feeding and morphological changes, more studies are needed to further understand the temporal offset between the two.