A Late Pleistocene third molar ofHylochoerus(Suidae, Mammalia) from Rusinga Island, Kenya: paleoenvironmental implications and a note on the hypsodonty of African forest hogs

Abstract

African forest hogs (genus Hylochoerus) are extant Afro-tropical suids that inhabit a variety of forest environments and thick bushlands and are predominantly herbivores. Hylochoerus likely evolved from a Pleistocene Kolpochoerus majus-like ancestor, but its recent evolutionary history is virtually unknown. Here, we describe a partial right lower third molar from the Late Pleistocene Wasiriya Beds of Rusinga Island (~50-36 ka). The crowns are mesiodistally compressed in a bunolophodont fashion and arranged in columnar pillars that resemble those of extant Hylochoerus. We provide accurate data derived from computed tomography on the hypsodonty index (HI) of extant Hylochoerus and show that the Rusinga third molar crown was as tall as those of its modern counterpart (HI = 1.8-2.0). Stable carbon isotope analyses suggest that the diet of the Rusinga specimen (δ 13 C = −17.0 ‰) was also like that of extant forest hogs (δ 13 C average = −17.6 ‰). This extremely negative value contrasts strikingly with those of other fossil large herbivores at Rusinga (δ 13 C average = −0.7 ‰.). Among the potential explanations for this anomaly, the most likely is that the Late Pleistocene paleoenvironments were more heterogeneous than previously considered and may have included closed-canopy woodland in the highlands of Rusinga.

Stable isotope (ẟ13C, ẟ18O) paleoecology of the late Early Miocene mammalian fauna from Buluk, Kenya

“…Other species of large-bodied kubanochoerine suids from Early Miocene deposits on Rusinga Island (Garrett, 2016) and the Middle Miocene deposits on Maboko Island (Arney et al, 2022) exhibit a much lower δ 18 O enamel signal relative to other fauna than M. marymuunguae from Buluk. At both Rusinga and Maboko Islands, kubanochoerine suids exhibit δ 18 O enamel values that are more depleted than most other herbivore taxa (Garrett, 2016;Arney et al, 2022), which is ecologically similar to the depleted δ 18 O enamel values of the extant, waterdependent giant forest hog (Hylochoerus meinertzhageni) and the red river hog (Potamochoerus porcus) (Harris and Cerling, 2002;Nelson, 2013;Cerling et al, 2015;Martin et al, 2015;Lazagabaster et al, 2021). The contrasting enriched δ 18 O enamel values of M. marymuunguae suggest feeding and/or drinking behavior that is unlike these extant taxa and other fossil kubanochoerines from localities with closed forest elements in the local habitat.…”

Suidae (Mammalia, Artiodactyla) from the late Miocene hominoid locality of Alsótelekes (Hungary)

“…The low oxygen isotope values observed for suids have been considered indicative of a frequent engagement in rooting (Eastham et al, 2016), as belowground resources such as tubers and rhizomes are lower in 18 O compared to leaf or fruit water (Dunbar and Wilson, 1983;Yakir, 1992), but the obligate drinking behavior of suids likely played an important role in influencing these observations (Kohn et al, 1996;Levin et al, 2006). For instance, low oxygen isotope values are also recorded in Hylochoerus (the extant African giant forest hog), a suid whose rooting activity is relatively limited (Lazagabaster et al, 2021). In any case, the consumption of underground resources by suids at Rudabánya is supported by the analysis of enamel strontium/calcium ratios (Eastham et al, 2017).…”