Chapter 3: Diet and ecology of extant and fossil wild pigs35
to place the morphology and diet of the suids within a larger
physiological (digestive system, body size, etc.) and ecological
context. When feeding, herbivorous mammals have evolved
different trade-offs between multiple morphological, physi-
ological, ecological, and behavioural variables to get enough
nutrients from the consumption and digestion of food: time
spent feeding, quantity of food ingested, efficiency in reducing
the food into digestible items, type and duration of digestion
(multi-chambered stomach, simple stomachs, rumination, cae-
cotrophy, etc.), body size. Those trade-offs have focused much
research and literature in ruminants and equids (e.g. Clauss
et al. 2008a) but no one, as far as the author knows, ever pro-
posed an explanation of suid herbivorous adaptations taking
into account those trade-offs. Here I propose a first preliminary
version of such a scenario.
First, previous studies considered both the length and height
of the third molars as comparable proxies for the degree of her-
bivorous adaptations. However, in terms of functional morphol-
ogy, both variables are obviously controlled by different factors.
Elongation of the third molars is likely related to chewing effi-
ciency as it multiplies the number of chewing sites. Elongated
teeth with numerous chewing sites are efficient for chewing
small food items (Lucas 2004: 169–170) and give an advantage
on a day-to-day fitness. Hypsodonty is rather linked to the dura-
bility of the tooth, i.e. its capacity to resist wear caused by phyto-
liths and grit contained in the food. A high crown gives a fitness
advantage on the scale of a lifetime.
The behaviour and ecology of extant warthogs within the
guilds of African herbivorous mammals are unique. Field obser-
vations indicate that they are able to feed on minute fragments
of grasses. Warthogs frequently feed on grass fields so short that
the grass blades are barely visible. I myself observed common
warthogs feeding on lands in the Pilanesberg National Park,
South Africa, shortly after fires: to a human eye, the land looked
pretty much barren, but the warthogs were able to feed on tiny
blades of grasses, and they were the only ungulates feeding there
(Figure 3.4). Similarly, warthogs are able to feed on grasslands
after they were grazed very short by other ungulates. By anal-
ogy with the extant warthogs, I propose here that most extinct
herbivorous suids that displayed dramatic adaptations of the
third molars were specialized on a diet of very small food items,
ingested in small mouthfuls.
Contrary to other ungulates (ruminants, tylopods, hippos,
tayassuids, equids, etc.), must suids do not display any special-
ized adaptations of the soft tissues of their digestive system to
cope with the plant matter, and especially the grasses. Their
stomach is composed of only one chamber, they do not rumi-
nate, and they do not have an enlarged caecum. That is also true
of the warthogs, even though their diets are composed almost
exclusively of grasses (Clauss et al. 2008b). Due to their limita-
tions in terms of digestive capacities of plant matter, herbivo-
rous suids need to reduce as much as possible the size of the
plant particles that enter the stomach.
A suite of morphological, ecological, and behavioural adap-
tations evolved to mitigate that problem: how to digest vegetal
matter without a specialized digestive physiology and stomach
anatomy? In suids, the emphasis when feeding on grass is the
selection of small and tender grass (ecology, behaviour) and the
buccal reduction of the grass into tiny digestible particles before
swallowing. On the contrary, equids and bovids are less limited
in terms of the types of vegetation they can feed on and the focus
is more on the post-swallowing digestion.Figure 3.4 Picture of a common
warthog (Phacochoerus africanus)
feeding on near-barren soil in the
Pilanesberg National Park, South
Africa. Photo by Antoine Souron..00512:31:27