An unusual specimen fell into the hands of paleontologists – a forked tooth of a megalodon, the largest shark in the history of the Earth. Researchers are trying to understand what could have caused such a defect – a developmental disorder or an injury that the shark received in life.
A photo: © National Geographic© National Geographic
Sharks are very ancient fish, the first of which appeared at the beginning of the Paleozoic era, about 450 million years ago. The skeleton of sharks, like other cartilaginous fish, is formed by cartilage and is usually poorly preserved. But we managed to find a lot of ancient shark teeth – thanks to them, we learned a lot of interesting things about ancient fish, the ancestors of the predatory great white and peaceful whale sharks, as well as their relatives.
Megalodon was the largest of these amazing creatures. Paleontologists believe that the huge shark reached a length of 15 or even 20 meters. To match this colossus were her teeth, sometimes growing up to 20 centimeters in length.
Teeth were beauty and pride megalodon, whose name is translated from Greek, in fact, as “big tooth”. Scientists suggest that, like modern sharks, megalodon had teeth that grew all their lives, in several rows, and were constantly updated, and therefore the fish could afford to lose a couple of them at dinner. But the most amazing thing is that they originated from shark scales and were arranged in much the same way.
In the new article in PeerJ, scientists described one unusual specimen of the tooth of the megalodon Otodus megalodon, and at the same time a pair of the so-called blunt-nosed sharks Carcharhinus leucas. Those were much smaller, but also swam in the seas of the Pliocene period 3.7-11 million years ago. It is curious that this species, unlike the completely extinct megalodon, was able to survive to this day.
What makes these Pliocene shark teeth unusual is a defect: they are all split lengthwise in two. To understand the reasons for such a dental feature, paleontologists performed computed tomography and compared the sample with the teeth of a “healthy shark” of the same species. It turned out that in bifurcated teeth, the dimensions of the internal canal are larger. This may be due to developmental pathology – possibly with partial fusion, but maybe with incomplete separation of two adjacent teeth.
“Our work was not easy, including because we had to apply the terminology that is accepted for humans and other mammals to sharks,” says Haviv Avrahami, a graduate student at the University of North Carolina (USA). “Sharks have a skeleton made of cartilage, not bones, so their jaws are poorly preserved as fossils, and usually all we have is individual teeth.”
As Haviv noted, the development of shark teeth can vary, so with just one single tooth at your disposal, it is difficult to understand what could be happening to its neighbors.
And yet, given the example of similar dental problems in living sharks, scientists are inclined to believe that the ancient tooth was split due to an injury that the shark received at dinner.
It is known that if the “conveyor belt” of the shark’s teeth growing inside the mouth and gradually moving outward is damaged by something, this can cause a similar pathology. So the ancient megalodon could have ruined his teeth, imprudently grabbing a spiny fish, getting a thorn prick from a stingray that just lived in the neighborhood, or some other injury.