The teeth of a 200 million years old reptile reveal how snakes got their fangs

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Snakes and other creatures have been menacing the world with venomous fangs since the early days of the dinosaurs, but until now nobody quite knew how they got their most fearsome weapon. Now a paleontologist has solved this evolutionary mystery.

Central to solving this mystery was the reptile Uatchitodon, a creature dating back to the late Triassic about 220 million years ago. Uatchitodon probably wasn't a dinosaur, but it was closely related to these creatures as well as crocodiles. Nowadays we only know the reptile from its teeth, but considering we're trying to figure out the evolution of fangs, that's not exactly a problem.

The teeth are tall and serrated, like those of a dinosaur or modern crocodile. The youngest specimens, which "only" date back to 220 million years ago, seem to have venom canals, which would make those teeth fangs. The older teeth that have been found have grooves in much the same place the canals would later be found, but definitely no sign that they could have held venom.


For a long time, scientists weren't sure how to proceed with the teeth - were the fangs from a later period of Uatchitodon's evolution as a species, from a later development stage in an individual's life, or maybe just teeth in a different position in the mouth from the other grooved pieces?

University of Chicago paleontologist Jon Mitchell has cracked the case, thanks to the recent discovery of 26 new Uatchitodon teeth. These teeth represent a middle age between the older grooved teeth and the younger fangs, and they capture a transitional stage in the evolution of the canals. They reveal the grooves became longer and deeper along the teeth until they eventually became enclosed canals.

Mitchell is fairly sure Uathitodon and snakes developed their fangs separately, but he also suspects they underwent much the same evolutionary process. So far, the response from others in the field has been very positive - University of Melbourne paleontologist says the fossil series Mitchell has put together is "fantastic" and is completely convinced by what's been put forward.

[Naturwissenschaften via New Scientist]