Tooth-shape adaptations in aglyphous colubrid snakes inferred from three-dimensional geometric morphometrics and finite element analysis

Abstract

<jats:title>Abstract</jats:title> <jats:p>To date there are few quantitative studies investigating the evolution of tooth shape and function in aglyphous snakes in relation to diet. A considerable evolutionary decrease in body size is observed in whip snakes of the genus Dolichophis and their sister-group Eirenis. This was coupled with a considerable shift in diet from a regime consisting mainly of prey with endoskeleton to prey bearing a hard exoskeleton. Three-dimensional (3D) geometric morphometrics revealed that the maxillary and palatine teeth of E. persicus are blunt and conical in shape, while the same teeth are sharp and elongated in E. punctatolineatus and D. schmidti. Blunt and conically shaped teeth, as observed in E. persicus, seem to be more adapted for biting hard-bodied, arthropod prey. In contrast, the sharp and elongated teeth in Dolichophis and E. punctatolineatus, are likely specialized for puncturing prey with an endoskeleton. The results of a finite element analysis confirms that during the biting of a hard-bodied prey, the generated stresses in E. persicus teeth are well below the von Mises yield criterion, while in D. schmidti the value is roughly two to three times higher, indicating that E. persicus teeth are better suited for biting hard-bodied prey such as arthropods.</jats:p>

Fang evolution in venomous snakes: Adaptation of 3D tooth shape to the biomechanical properties of their prey

“…When considering nonfang teeth in snakes, adaptations to diet have been found in previous research. Recently, a similar trend of variation in tooth sharpness and robustness with prey hardness was found in palatine and pterygoid teeth of Colubridae (Rajabizadeh et al., 2020). Another recent study looked at tooth number, and the length of individual teeth and the maxilla in Colubridae and found a correlation with both diet and capture method.…”

“…The penetrative ability of teeth has been studied recently on colubrid palatine and pterygoid teeth where they modeled the penetrative ability of hard exoskeletons by both robust and slender teeth (Rajabizadeh et al., 2020), as well as spider fangs (Bar‐On et al., 2014), using finite element analysis (FEA). In colubrids, stresses in robust teeth are more confined to the tip of the tooth while staying below the von Mises yield criterion, thus resisting the loading well (Rajabizadeh et al., 2020).…”

“…The penetrative ability of teeth has been studied recently on colubrid palatine and pterygoid teeth where they modeled the penetrative ability of hard exoskeletons by both robust and slender teeth (Rajabizadeh et al., 2020), as well as spider fangs (Bar‐On et al., 2014), using finite element analysis (FEA). In colubrids, stresses in robust teeth are more confined to the tip of the tooth while staying below the von Mises yield criterion, thus resisting the loading well (Rajabizadeh et al., 2020). In contrast, when using slender teeth with sharper tips to penetrate hard materials, the von Mises stresses were well above the tooth yield criterion on multiple locations, indicating the likely positions where these teeth would break if those loads were reached during feeding (Rajabizadeh et al., 2020).…”

“…In colubrids, stresses in robust teeth are more confined to the tip of the tooth while staying below the von Mises yield criterion, thus resisting the loading well (Rajabizadeh et al., 2020). In contrast, when using slender teeth with sharper tips to penetrate hard materials, the von Mises stresses were well above the tooth yield criterion on multiple locations, indicating the likely positions where these teeth would break if those loads were reached during feeding (Rajabizadeh et al., 2020). Spider fangs with a more robust shape had a better load‐bearing capacity compared to the slender design, particularly at the base (Bar‐On et al., 2014).…”

A new species of snake of the genus Oligodon Boie in Fitzinger, 1826 (Reptilia, Serpentes) from the Western Himalayas

“…This could be an adaptation for a shift in the diet that largely comprises of reptile and or bird eggs. Modification of teeth in snakes is driven by its diet (Hoso et al 2007;Rajabizadeh et al 2021) and vestigial or loss of teeth is seen in snakes that feed on eggs (Gans and Oshima 1952;Gans and Williams 1954;Vitt and Caldwell 2013). Dietary investigations of the species would be necessary to confirm the preceding hypothesis.…”