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Snake fangs tell a story of tooth evolution

Snake fangs tell a story of tooth evolution

Venom fang of a Gaboon viper, with the venom groove running along the top. Alessandro Palci, Author provided

Full article published in The Conversation.

ARC-supported research has revealed how snakes' teeth have evolved in so many different ways to deliver venom. The research team based at Flinders University, and supported by a Discovery Projects grant, has shown that this tooth evolution occurred via a modification of tooth structures that may have served to help anchor the teeth in their sockets.

The researchers were interested in how snakes repeatedly evolved syringe-like teeth for delivering venom from the simpler cone-shaped teeth of their ancestors. To answer the question, they took a close look at the teeth of 19 species of snakes, including both venomous and non-venomous species and one early fossil form.

Using both traditional methods, such as studying slides under a microscope, as well as cutting-edge microCT scans and biomechanical modelling, the team found that nearly all snakes, whether venomous or not, have teeth that are tightly infolded at their base, and look 'wrinkly' in cross-section. It had been suggested that the folds had evolved to strengthen the teeth, but the researchers found that this was not the case, but they may assist with tooth attachment.

The team also found that in venomous snakes, their teeth have one large fold that extends up the tooth to produce a groove: the venom groove. They suggest that when a grooved tooth appeared near the discharge orifice of the venom gland, these structures evolved into grooves running along the whole length of the tooth, which served as a handy conduit to deliver venom.

This discovery shows how a simple ancestral feature, such as wrinkles on the tooth base, can be modified and re-purposed for a completely new function (a groove for venom injection). The researchers say that this could help explain why snakes, uniquely among all animals, have evolved venomous fangs so many times.


Image Credit: Alessandro Palci. Venom fang of a Gaboon viper, with the venom groove running along the top. 

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