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Scientists track anatomy behind our smiles

Posted on Oct 18, 07:05PM | IANS

Both jaws and teeth are parts of the anatomy that help make a pretty smile, but their evolutionary origins have just been discovered, thanks to a particle accelerator and a long dead fish.

All living jawed vertebrates (animals with backbones, such as humans) have teeth, but it has long been thought that the first jawed vertebrates lacked pearly gnashers, instead capturing prey with gruesome scissor-like jaw-bones.

However, new research, led by the UK's University of Bristol, shows that these earliest jawed vertebrates possessed teeth too, indicating that teeth evolved along with, or soon after, the evolution of jaws, the journal Nature reports.

Palaeontologists from Bristol and the Natural History Museum and Curtin University, Australia, collaborated with physicists from Switzerland to study the jaws of a primitive jawed fish called Compagopiscis.

The international team studied fossils of Compagopiscis using high energy X-rays at the Swiss Light Source at the Paul Scherrer Institute in Switzerland, revealing the structure and development of teeth and bones, according to a Bristol statement.

"We were able to visualise every tissue, cell and growth line within the bony jaws, allowing us to study the development of the jaws and teeth. We could then make comparisons with the embryology of living vertebrates, thus demonstrating that placoderms possessed teeth," Martin Ruecklin of Bristol said.

"This is solid evidence for the presence of teeth in these first jawed vertebrates and solves the debate on the origin of teeth," co-author Philip Donoghue, professor at Bristol's School of Earth Sciences said.

"These wonderfully preserved fossils from Australia yield many secrets of our evolutionary ancestry but research has been held back waiting for the kind of non-destructive technology that we used in this study," co-author Zerina Johanson from the Natural History Museum said.

"Without the collaborations between palaeontologists and physicists, our evolutionary history would remain hidden in the rocks," Johanson added.