Did tooth enamel evolve from fish scales?
The enamel that protects our teeth may have evolved from the scales of ancient fish, a new study published in the journal Nature says.
Enamel resembling a tissue called guanine that is found on the scales of many fossil and primitive fish. But enamel is only found on our teeth.
When scientists studied fossils of two primitive bony fish from the Silurian Period, some 400 million years ago, they found that there was an enamel coating their scales, but none on their teeth.
Only millions of years later did fish evolve to use enamel to make teeth harder and stronger.
"This is important because it is unexpected. In us, enamel is only found on teeth, and it is very important for their function, so it is natural to assume that it evolved there," said palaeontologist Professor Per Erik Ahlberg of Sweden's University of Uppsala.