The scales of a 420-million-year-old fish may be the reason why we now have enamel on our teeth, a new study suggest.
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Scientists say they figured this out by analyzing the fossils of lengthy-lifeless fish, in addition to the DNA of a spread of creatures alive immediately. They make their case in a report published online Wednesday by the journal Nature. It’s the hardest substance produced by the body, and is made up of the mineral apatite, or calcium phosphate.
Enamel is present in nearly all four-limbed creatures like mammals, birds, amphibians and reptiles. It would appear that the materials our body emits to create enamel originated in our skin and, as we evolved, moved to our teeth. Another called Psarolepis, from 418 million years ago in China, had enamel on its scales and also the bones of the face.
The genes required in making such kind of hard tissues are mainly the same, and majority are clustered together in the genome.
Besides finding genes expressed for enamel proteins in both humans and gar fish, researchers established that Psarolepis and Andreolepis had enamel on their scales but no enamel in mouths. However, the research also pointed out that most of the fish don’t produce any enamel. He, along with many other experts never thought that the substance evolved from something else than denture, considering that it is a key component of our teeth.
According to paleontologist Qingming Qu from the Uppsala University and the University of Ottawa, enamel in our teeth are normally used for biting or shearing, enamel was originally used as a protective tissue found in living primitive such as gars and bichirs. Specimens have been found with enamel on their scales but not on bones in the skull. The lack of enamel in the teeth of the earliest bony fish shows that they were prototypical and primitive.
Researchers are imagining potential uses that fish could have drawn from enamel on their skin.
The team noted that although he prehistoric fishes both have enamel on their scales, it was only a thin layer of tissue.
Some researchers are now saying that the dead Psarolepis Romeri and Andreolepis Hedei may be the same species. “It seems that enamel originated in the skin, where we call it ganoine, and only colonized the teeth at a later point”, study co-author Per Ahlberg, professor of evolutionary organismal biology at Uppsala University, said in a press release.
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Like other land vertebrates we only have teeth in the mouth, but certain fishes such as sharks also have “dermal denticles” – little tooth-like scales – on the outer surface of the body.
