Gross morphology, length, curvature
From the sharp, elongated and nearly straight teeth of the ball python (Python regius , Fig. 4), to the round, bulky and nearly flat teeth of the king cobra (Ophiophagus hannah ; Fig. 4), the morphological variability of dentary teeth in snakes is far larger than what transpires from the literature. Yet, snake teeth remain easily identifiable among vertebrates as they share some characteristics: they are all conical, with various degrees of sharpness, and –although to different degrees— posteriorly and medially curved (Fig. 2-5). Variation in our curvature measurements appears to be driven by both intrinsic and extrinsic factors. The mean and maximal degree of curvature are significantly but weakly related to tooth length (Fig. 2). They are positively correlated with one another; it was not obvious that this relationship existed as the overall curvature can either be caused by an elbow-like shape (high maxima of curvature, e.g., Homalopsis buccata , Fig. 4) or a continuous curvature (high mean curvature, e.g.,Laticauda colubrina , Fig. 2). Yet, our results show that more curved teeth also have a larger maximal angle of curvature and overall straighter teeth have a smaller maximal angle of curvature. A posterior tooth curvature may reduce the risk of breakage when the snake strikes at high velocity and acceleration (Ryerson & Van Valkenburgh, 2021). An increase in the curvature is associated with a decrease in the maximal stress undergone by the teeth when out-of-plane forces are involved, which is likely to be the case during a feeding sequence. The curvature may also allow the prey to slide over the teeth into the mouth and to be impaled if moving backwards, thus preventing a potential escape.