Dietary factors
An extensive bibliographic study was performed to characterize the diet,
feeding behavior, and ecology of the 63 species (Supplementary Material
1). Following our hypotheses, we defined four factors that could impact
the shape of the teeth in snakes: prey hardness, prey shape, feeding
substrate and main mechanical challenge. We defined the three levels of
prey hardness: soft (e.g., gastropods, annelids, birds, mammals), medium
(e.g., amphibians, fishes, thin-scaled lizards such as anoles), and hard
(insects, crustaceans, snakes, hard-scaled lizards such as skinks,
Savitzky, 1983). Prey shape has two levels: bulky or long following
descriptions in Segall et al. (2020). Mammals are considered bulky as
the hind limbs are particularly difficult to swallow and require
extensive manipulation in snakes. For generalist snakes that do not show
a preferred prey, we did not attribute them to any prey shape group
(“na” in Supplementary Material 1). The foraging substrate has three
levels: ground, water, and branch depending on where the swallowing of
the food occurs. The main mechanical challenge encountered by snakes
while feeding has five levels: hard (chitinous preys, hard-scaled
lizards), long (snakes, soft-scaled lizards, earthworms), hold (snakes
that maintain vigorous preys), slippery (fish, snails, amphibian eggs),
bulky (mammals, amphibians).