Snakes change their teeth in a unique way among reptiles

17 Feb. () –

The discovery of the mechanism that allows snakes to shed their old teeth has revealed key differences compared to other reptiles, in a study at King’s College London.

Most reptiles constantly replace their teeth with new ones. However, the teeth of snakes do not show signs of how old teeth are removed from the jaw. In contrast, other reptiles have a “replacement pit” that forms when a new tooth begins to grow. This socket of substitution eats away at the base of the older tooth and helps it break loose in a process known as external tooth resorption.

The results of the study reveal that snakes lack these pits and are able to shed old teeth thanks to the unusual action of odonoclasts (cells that remove dental tissues), that break down the dentin inside the tooth.

The results of the study show that this internal resorption of the teeth can even be detected non-invasively, using computed tomography. Combining these methods, the researchers revealed that this unique form of tooth replacement is found throughout the evolutionary tree of snakes.

“As new discoveries of older fossil snakes push their origins back to the age of the dinosaurs, there may come a time when the lines between ‘lizard’ and ‘snake’ seem blurry. We need unique anatomical markers for snakes, which are preserved both in living and extinct species and that can be identified in fossils.From this mechanism of shedding of teeth in modern snakes, we can provide a new line of evidence, independent of the anatomy of the skull and body, that supports the identification of fossil jaws as belonging to primitive snakes,” says it’s a statement Dr. Aaron LeBlanc, lead author of the study and professor of Dental Biosciences in the School of Dentistry and Oral and Craniofacial Sciences.

Replacing teeth in snakes has no equivalent in other lizards or any other reptile. At some point in the life of each snake tooth, it undergoes a dramatic transformation: the internal pulp of each tooth is filled with large cells that begin to eat away at it from within. This process ends up weakening the base of the tooth enough to separate it from the jaw, allowing the new tooth to settle into position and replace its predecessor.

Using computed tomographythe researchers looked inside skeletons of extant species and identified “bite marks” on the dental tissues left behind by odontoclasts that would have been resorbing the inside of the tooth.

The researchers then used this method to detect these “bite marks” inside the teeth of the Yurlunggur fossil snake and one of the oldest snake fossils, a 150-million-year-old Portugalophis jaw fragmentsuggesting that this is one of the earliest innovations in the snake lineage, predating even the loss of limbs.

The work is published in the journal Nature Communications.