Prey hardness
As predicted, snakes eating hard prey have short, stout, blunt and less
posteriorly and medially curved teeth, contrary to softer-prey eaters
that have long, slender, and more curved teeth (Fig. 3 & 5). Compared
to slender teeth, short and stout teeth undergo a relatively smaller
maximal stress coming from the compression force and the stress is
concentrated at the tip of the tooth (Bar-On, 2019; Rajabizadeh et al.,
2020). This may reduce the risk of failure of the tooth while feeding on
hard items but may cause fragmentation and wear of the tip. We noticed
some tooth fragmentation in species such as Fordonia leucobalia .Fordonia is a peculiar species that feeds on crustaceans that are
crushed and dismembered (Jayne et al., 2018). This behavior likely
imposes high load on the teeth, thus aggravating the fragmentation. Most
durophagous snakes do not use their teeth to dismember their prey, or to
crush them like other vertebrates. They use their teeth to manipulate
and swallow their prey (sometimes alive Arsovski et al., 2014).
Consequently, they may not need to resist loads as high as other
vertebrates. In fact, durophagous snakes generally do not pierce their
prey, they only have superficial, but repeated contacts with it during
capture and manipulation. These snakes may have evolved short and blunt
teeth to limit fracture during capture and manipulation, but this tooth
shape seems to be related with high prey escape rate, and the necessity
for behavioral adjustments, such as coiling the body around the prey to
limit losing the prey (Gripshover & Jayne, 2021). Some durophagous
snakes have independently evolved hinged teeth that fold back when they
swallow the prey but may rise up if the prey moves backwards, a strategy
preventing escape as well (Jackson et al., 1999; Savitzky, 1981). Some
legless lizards specialized on eating hard scaled lizards show a similar
specialization suggesting a convergent evolution of hard-prey
specialists in squamates (Patchell & Shine, 1986). On the other hand,
the dentary teeth of snakes feeding on softer prey show morphological
adaptations related to piercing and getting a grip on prey and
preventing escape, such as an elbow-like configuration and a sharp tip.