The link between our teeth and fish scales

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Humans aren’t generally attached to scales, but we need to start thinking differently, according to a dental study.

How were the teeth formed? Teeth that ensure you as an animal that you can suddenly grab prey or plants better and that you can also split them more easily. According to the researchers, it all started with one type of fish. Animal ancestors with their teeth.

But even then: How did these teeth originate? According to one theory, the scales on the outside of the fish migrated to the inside of the mouth. Another sees it the other way around: just like the gill tissue, the teeth must have grown from the inside.

This new study looked at sawfish to clarify which theory is more appropriate. Researchers studied 70-million-year-old fossils of an extinct species of sawfish. Specifically, they looked at the pointed protrusions on the animal’s nose, which is why the word saw appeared in the name. These pointed protrusions are often referred to as teeth, but are actually specialized scales.

When they looked at the structure of the outer layer of these scales under a microscope, they were surprised to see that this structure is quite similar to the teeth of modern sharks. Swordfish also have true teeth in addition to these scales, so it didn’t change its placement in this animal, but it does show that scale-like structures can easily evolve into tooth-like structures. Plus sign for the “outside in” theory. Just think about it next time you clean the scales.

Read more: Sawfish fossils indicate that teeth likely evolved from body scales in ancient fish.