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Chapter

3

Diet and Ecology of Extant and Fossil Wild Pigs

Antoine Souron

Introduction

Most extant wild pig species (Suidae) are omnivorous and con-
sume a large variety of foods, including animal matter, plant
matter (leaves, grass, forbs, ferns, fruits, nuts, roots), fungi,
faeces, and even soil (e.g. Meijaard et al. 2011). Species of the
genera Babyrousa, Sus, and Potamochoerus are omnivorous and
comprise the large majority of the specific diversity containing
13 of 17 species recognized by a recent synthesis (Meijaard et al.
2011).
Extant omnivorous suids all display similar cranio-mandibular
and dental morphologies (see below) adapted to process a wide
array of food items. Most extinct suids display morphologies simi-
lar to those of extant omnivorous suids. By analogy, they are usually
considered to be omnivorous.
I will focus here on the exceptions within the Suidae family
and review the morphological and ecological data that docu-
ment how some species of African suids became adapted to
more specialized diets dominated by plant matter, and espe-
cially grasses. Herbivorous suids belonging to the subfamilies
Tetraconodontinae and Suinae in Africa diversified during the
last 10 million years. The extant giant forest hogs (Hylochoerus)
and warthogs (Phacochoerus) are the only relics of those
radiations, being descendants of the Plio–Pleistocene gen-
era Kolpochoerus and Metridiochoerus, respectively (Harris &
White 1979; Souron et al. 2015a).

Climatic and Environmental Background

Strong climatic changes occurred during the Neogene and
Quaternary periods with a global trend to a cooler global climate
and a drier climate in tropical Africa (e.g. deMenocal 2004). The
expansion of tropical grasslands dominated by grasses using
the C 4 photosynthetic pattern is well documented based on
stable carbon isotopes of paleosols and mammal teeth, as well
as paleobotanical remains (Bonnefille 2010; Uno et  al. 2011;
Cerling et al. 2015).
Roughly synchronous with those climatic and vegetation
changes, dramatic changes in the faunas are also documented,
notably in the rich fossil record of eastern Africa. Various mam-
mals with strong dental adaptations to the consumption of abra-
sive grasses (hypsodonty, megadonty, etc.) become more and
more abundant as the landscapes changed. The African suids
form a part of this diversification and they started exploiting C 4
grasses during the late Miocene, after most other groups of her-
bivorous mammals (Uno et al. 2011). The details of the faunal

changes are subject to much debate (continuous replacement in

Bibi & Kiessling 2015 versus pulse turnovers in other studies).

Taxonomic and Phylogenetic Framework

Due to the rampant convergent evolution towards similar

dental morphologies and the fragmentary nature of the first

fossils discovered, the species-level taxonomy of the African

Tetraconodontinae and Suinae is still much debated (e.g.

Boisserie et al. 2014; Souron et al. 2015a).

The genus Nyanzachoerus first occurred in Africa some time

during the middle Miocene (following a dispersal event from a

Eurasian ancestor) and became abundant after 8 Ma with at least

eight species recognized by a recent study (Boisserie et al. 2014).

Around 4 Ma, Nyanzachoerus gave rise to the more derived genus

Notochoerus, represented by at least four species (Figure 3.1).

The genus Kolpochoerus first occurred in Africa around

5.5 Ma and around eight species are known (Souron 2012;

Souron et al. 2015a). It was first represented by a single lineage

(divided into two to three chronospecies) during the Pliocene,

followed by a modest radiation giving rise to six species dur-

ing the Pleistocene (Figure 3.2). Kolpochoerus gave rise to the

extant genus Hylochoerus sometime during the Pleistocene, but

the fossil record of the latter is extremely scarce (Souron 2012;

Souron et al. 2015a).

The genus Metridiochoerus first occurred in Africa by at least

3.4 Ma (White et al. 2006) and possibly earlier, by 3.8 Ma (Souron

2012). There was a modest radiation during the Pleistocene

(around seven species) and it gave rise to the extant genus

Phacochoerus. Again, the fossil record of the latter is scarce and

it is difficult to decipher the timing of the origin of Phacochoerus

(Figure 3.3).

Methodology

Most paleoecological reconstructions for extinct African suids

are based on: (1) ecomorphology of teeth; and (2) stable carbon

isotopes of the enamel.

Ecomorphology

Ecomorphology uses the relationship between the ecology and

morphology of extant mammals as a guide to understand the

ecology of extinct mammals. The evolutionary history of African

suids left us with three extant genera with extreme ecologies and

morphological adaptations, encompassing most morphological

disparity found in their extinct relatives.

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