Postcranial skeletal morphology in living and fossil African suidae

This paper examines the postcranial adaptations and functional morphology of modern and fossil Afrotropical pigs, particularly as they relate to habitat preference. Pigs are large-bodied dietary generalists (Hatley & Kappelman 1980). Fossil pigs are widespread and relatively common in the African fossil record, which gives us the opportunity to examine their skeletons in the past and in the present. In East Africa, where their fossil record is particularly good, their evolutionary history is relatively well known and is the basis for biostratigraphic correlations throughout the continent (Cooke 1967 et seq.; Cooke and Wilkinson 1978; Harris & White 1979; Harris 1983). The earliest-known Suidae are from the Oligocene of Eurasia (Savage & Long 1986; Carroll 1988; Orliac et al. 2010a, 2010b; Bishop et al. 2011; see also Chapter 1 of this volume). Whereas all other even-toed ungulates (Mammalia: Artiodactyla) developed dentitions with selenodont cusps, only pigs, peccaries, and hippopotami retained bunodont dentition. Although there is some disagreement on taxonomy and evolutionary relationships, a consensus view holds that four extinct and three living genera occurred during the Pliocene and Pleistocene of Africa (Cooke & Wilkinson 1978; Cooke 1978a, 1978b; Harris & White 1979; Bishop et al. 2011; see also Chapter 1). There are three major radiations that took place: Nyanzachoerus → Notochoerus, Kolpochoerus → Hylochoerus (and Potamochoerus), and Metridiochoerus → Phacochoerus (Cooke 1978a, 1978b; Harris & White 1979; White 1995). The earliest of these, Nyanzachoerus → Notochoerus, were archaic tetraconodont pigs and went extinct without issue. The outcome of the other radiations of suine pigs differs substantially. The modern survivor of the Metridiochoerus lineage is a derived genus, the warthog Phacochoerus. The bushpig Potamochoerus, a modern representative of the Kolpochoerus radiation, is a conservative representative of it, occuring rarely throughout the fossil record in a form very close to its modern appearance. The other taxon thought to have its genesis in that lineage, the (giant) forest hog, Hylochoerus, is derived in several aspects but has a poor fossil record. At times, some fossil sites preserve up to six sympatric and co-occurring suid taxa (Harris & White 1979; White 1985; Foley 1987).