typhlonectes: How the Enamel Coating Your Teeth Evolved from Ancient Fish Scales by Sid Perkins The
typhlonectes:How the Enamel Coating Your Teeth Evolved from Ancient Fish Scalesby Sid PerkinsThe hardest bit of your body is the enamel coating your teeth. But new analyses of fish fossils, as well as genetic analyses of a living fish species, suggest that this specialized material once served a very different function: to toughen some bones and scales of ancient fish. The findings bolster earlier suggestions that ancient fish had enamel-armored scales, and they point to a new scenario for exactly how the substance ended up on teeth.Enamel—an almost pure layer of a mineral called hydroxyapatite—coats the teeth of almost all tetrapods (four-limbed creatures) and lobe-finned fish such as coelacanths. Most living fish do not produce it, but Per Ahlberg, a paleontologist at Uppsala University in Sweden, found an ancient exception. Well-preserved fossils of an ancient fish called Psaroepis romeri reveal that this 20-centimeter-long minipredator, which prowled the seas between 410 million and 415 million years ago, had enamel in its scales and its skull—but not its teeth, according to a paper by Ahlberg and colleagues in the 24 September issue of Nature…(read more: Science/AAAS)images: T - Nobu Tamura; B - Min Zhu and Qingming Qu -- source link