Fossil Suidae (Mammalia, Artiodactyla) from Lee Adoyta, Ledi-Geraru, lower Awash Valley, Ethiopia: Implications for late Pliocene turnover and paleoecology

The fossiliferous late Pliocene deposits of the Lee Adoyta sub-basin, lower Awash Valley (LAV), Ethiopia, sample a poorly-known time interval in this region (~2.82 to <2.5 Ma). Recent fieldwork in Lee Adoyta by the Ledi-Geraru Research Project has produced a rich mammalian fauna, including the earliest specimen of the genus Homo. Here, we describe the fossil Suidae (pigs) and provide taxonomic and paleoecological comparisons with other sites in the LAV (e.g., Hadar, Woranso-Mille). The Lee Adoyta suid fossils document the presence of at least three species, including Notochoerus cf. No. capensis, Kolpochoerus phillipi, and Metridiochoerus andrewsi, all of which are absent from the older deposits in the LAV (>2.95 Ma). However, two of these species (No. cf. No. capensis and K. phillipi) have likely ancestors known from the Hadar Formation (No. euilus and K. afarensis), implying a continuity of suid lineages through the Pliocene LAV. A compilation of stable carbon isotope (δ13C) data show a trend from C3-C4 mixed diets at Hadar to C4-dominated diets by ~2.82 Ma at Lee Adoyta, most likely C4 grasses. Suids decline in abundance almost linearly from ~3.76 to <2.5 Ma in the LAV, which we propose is related to the expansion of open, grassier habitats during this time.