Researchers have analysed the jaws of a primitive fish called Compagopiscis and found that jaws and teeth evolved almost simultaneously.
Image: Esben Horn, 10tons; supervised by Martin Rücklin, John Long and Philippe Janvier
It takes both to smile, but the evolutionary origins of teeth and jaws have only just been discovered, using particle physics and an old Australian fish fossil.
Many have thought the first jawed vertebrates captured prey with toothless, scissor-like jaw-bones. However, new research published in Nature shows the earliest jawed vertebrates possessed teeth too, indicating that teeth evolved along with, or soon after, the evolution of jaws.
Palaeontologists from Curtin University, University of Bristol and the Natural History Museum collaborated with physicists from Switzerland to study the jaws of a primitive jawed fish called Compagopiscis.
The international team studied the Australian fossils of Compagopiscis using high energy X-rays at the Swiss Light Source at the Paul Scherrer Institut in Switzerland, revealing the structure and development of teeth and bones, without affecting the fossil.
Co-author Kate Trinajstic, of Curtin’s Department of Chemistry, said the research team was able to use new technology to visualise every tissue, cell and growth line within the bony jaws and study its development. The team then made comparisons to the embryology of living vertebrates, determining that placoderms, ancient armored fish that were the first fish to have jaws, also possessed teeth.
“It was a great achievement to finally solve the debate on the origins of teeth,” she said.
“We’ve always known exceptionally preserved fossils, such as those from Western Australia, hold a lot of answers to many evolutionary questions, but research like this has been waiting for non-destructive technology to study fossils without touching them.”
The research team used a particle accelerator called a synchrotron as the X-ray source for performing non-destructive 3D microscopy of the sample.
It allowed the team to make a perfect computer model of the fossil that could be cut up in any way they wanted without damaging the fossil.
“We would never have got the permission to study these unique fossils otherwise,” Dr Trinajstic said.This work was funded by the EU Framework Programme 7, the Natural Environment Research Council and the Paul Scherrer Institut.
The paper, Development of teeth and jaws in the earliest jawed vertebrates, is available at www.nature.com.
Editor's Note: Original news release can be found here.