Prehistoric fish the first to grow a set of teet

Nicky Phillips

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Big bite ... a sculptured reconstruction of the placoderm. Photo: Esben Horn

Scientists have found fossil evidence of the first animal to grow a set of pearly whites — a prehistoric fish that lived more than 380 million years ago.
An international research team discovered teeth in several specimens of an ancient fish species, known as placoderms, a finding that likely represents the origins of teeth and jaws in animals.
A full set of chompers has been key to the success of most top predators.
One of the group's researchers, Kate Trinajstic, from Western Australia's Curtin University, said the development of teeth meant placoderms, which were covered in plates of bony armour, could become a top predator who ruled the oceans for more than 70 million years.

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"This was the point in history where animals with teeth and jaws started to take over," said Dr Trinajstic.
"And when you look at our world today, the dominate vertebrates are the ones who have teeth and jaws," she said.
The ancient fish are one of man's oldest ancestors.
"They're the most ancient of the jawed vertebrates and we are a jawed vertebrate as well."
The structure and function of teeth has remained largely unchanged over several hundreds of millions of years, which suggested their development had been highly successful.
The next evolutionary step was teeth that could fall out and be replaced. Unlike humans, placoderms had only one set of teeth for life.
It has taken more than half a century and a series of technology advances for scientists to confirm the prehistoric fish had teeth.
"The problem has been that to look at teeth you have to look at internally and museum directors aren't too fussed on the idea of cutting up their specimens," said Dr Trinajstic.
The team analysed several placoderm specimens, from a fossil deposit in western Australia known as the GoGo formation, using a synchrotron in Switzerland that showed the fish had true teeth, featuring a pulp canal, dentine and enamel, without damaging the fossils.
"It was really good to be able to solve the problem once and for all," she said.
The findings are published in the journal Nature today.

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Read more: http://www.watoday.com.au/world/science/prehistoric-fish-the-first-to-grow-a-set-of-teeth-20121018-27sae.html#ixzz2CqM6L9jW