Recently, researchers from the Uppsala University and the Institute of Vertebrate Paleontology and Palaeoanthropology (IVPP) in China, gathered in order to find evidence regarding the enamel that protects our teeth. The data showed that the enamel was originated in the scales of fish that existed 400 million years ago. The research was published in the Journal Nature.

The enamel is the thin outer covering of our teeth. This tough shell is the hardest and maybe strangest tissue in the human body, the substance covers the crown which is the part of the tooth that is visible outside of the gums. Until now, scientist have struggled to figure out the beginnings of the tissue.

Onychodus is a genus of prehistoric lobe-finned fish which lived during the Devonian period. Suggestions by palaeontologist John A. Long refer to a close phylogenetic relationship between Onychodus and the basal lobe-finned fish Psarolepis from China. Credit: Wikipedia

The origin of Enamel

The scientists combined data from two fossil fishes – Psarolepis from China and Andreolepis from Sweden – both species are more than 400 million years old and have been investigated by Uppsala University and the IVPP in order to get some answers.

The results showed that in Psarolepis, the scales and the denticles of the face were covered with enamel, but what caught the attention of the researchers was that there was no enamel on the teeth – the same happened with Andreolepis fossils, only the scales had the substance. Which led them to the conclusion that enamel was first originated in the skin and it established on the teeth much later.

Moreover, the researchers discovered that in most of the fossil fishes and archaic living ones like Lepisosteus from North America, the scales are made up with an enamel-like tissue, named “ganoine.”

This investigation is the first to link novel palaeontological and genomic data in one single research to figure out tissue evolution. The researchers are planning to go further with this investigation in order to discover the evolution of vertebrate hard tissues using this technique.

“Psarolepis and Andreolepis are among the earliest bony fishes, so we believe that their lack of tooth enamel is primitive and not a specialization. It seems that enamel originated in the skin, where we call it ganoine, and only colonized the teeth at a later point” explained Per Ahlberg, Professor of Evolutionary Organismal Biology at Uppsala University.

Source: Uppsala University