(ORDO NEWS) — Researchers have described key differences in tooth replacement between snakes and other reptiles for the first time.
Unlike other reptiles, in snakes, old teeth fall out as a result of the action of odontoclast cells, which destroy their structure from the inside.
This unique feature appeared in the evolutionary history of snakes even before the loss of limbs. Most reptiles, unlike mammals, change their teeth many times during their lives.
Basically, this process begins with the formation of the so-called replacement fossa, which is formed on the jaw when a new tooth begins to grow.
It corrodes the base of the old tooth and helps it fall out. Snakes, on the other hand, do not have a removable fossa, and their jaws do not retain any traces of numerous changes of teeth.
Now scientists from King’s College London (UK) have described how the process of changing teeth occurs in snakes.
It turned out that it is provided by special large cells – odontoclasts, which destroy the dentin from the inside of the tooth.
This process weakens the base of the tooth enough that it breaks away from the jaw, allowing the new tooth to be forced into place.
Every year, scientists discover more and more new species of ancient fossil snakes dating back to the very beginning of the evolutionary history of these reptiles.
Therefore, sometimes the boundaries between “lizard” and “snake” seem blurred.
Researchers are looking for anatomical features unique to both living and extinct snake species that will allow accurate identification of fossils.
From this point of view, the mechanism for changing teeth turned out to be the very anatomical feature unique to snakes.
Using computed tomography techniques that can examine the structure of a tooth without destroying its integrity, scientists have shown that a unique form of tooth replacement occurs throughout the evolutionary tree of snakes.
First, the authors of the work looked inside the teeth of the skeletons of living species and found traces of odontoclast activity there.
The researchers then used tomography to reveal traces of odontoclasts inside the teeth of a giant fossil snake from the genus Yurlunggur, as well as one of the oldest known snakes, Portugalophis, which lived about 150 million years ago.
A similar mechanism for changing teeth appeared in snakes even before they completely lost their limbs.
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