October 18, 2012
Researchers Find Origins Of Teeth Much Older Than Previously Believed
Michael Harper for redOrbit.com — Your Universe Online
It´s likely the question “how long have humans had teeth?” has never entered into many normal and sober minds. Scientists and, more specifically, odontologists, are a different breed, however, and have wondered about the origins of teeth for many years.
Now, thanks to a particle accelerator and a very, very dead fish, scientists have concluded that teeth may be much older than they had previously assumed.
The qualifications to earn a set of pearly whites are simple: A creature must be a vertebrate (have a backbone) and must have a jaw. If a creature (humans included) is in possession of these 2 elements, they will always have teeth. However, it had long been assumed that the oldest of these jaw-having vertebrates didn´t have teeth, using instead a set of scissor-like jaws with which to capture and eat food.
Some researchers at the University of Bristol have gone sniffing around this theory and smelled something fishy, sending them on a mission to discover where teeth had first arrived on the evolutionary tree.
Working together with paleontologists from Bristol, the Natural History Museum and Curtin University, Australia and physicists from Switzerland, Martin Ruecklin and team began to study the jaws of a primitive fish named Compagopiscis.
Using the Swiss´ particle accelerator, the international team began shooting high energy X-rays at the jawbone of the Compagopiscis. What they found had surprised them, as well as chewed some holes in the previous knowledge about how early our vertebrae ancestors began gnawing instead of scissoring.
“We were able to visualize every tissue, cell and growth line within the bony jaws, allowing us to study the development of the jaws and teeth,” said Ruecklin, who is also the lead author of the resulting paper which was published today in the journal Nature. “We could then make comparisons with the embryology of living vertebrates, thus demonstrating that placoderms possessed teeth.”
Ruecklin´s co-author, Professor Philip Donoghue of the University of Bristol´s School of Earth Sciences, backed up his claims in the press release, saying: “This is solid evidence for the presence of teeth in these first jawed vertebrates and solves the debate on the origin of teeth.”
Other members of the global team also expressed their excitement and near-surprise that teeth have been around, evolutionarily speaking, for as long as they have. In fact, the team members were so excited by this finding, they began to wonder aloud what other discoveries are hiding in the well preserved Australian fossils.
“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,” exclaimed Zerina Johanson from the Natural History Museum, another co-author of the newly published paper.
“Without the collaborations between palaeontologists and physicists, our evolutionary history would remain hidden in the rocks.”
Professor Marco Stampanoni, a Swiss scientist with the Paul Scherrer Institut, explained the way the particle accelerator was able to help the team find the long-misunderstood origin of teeth.
“We performed non-invasive 3D microscopy on the sample using synchrotron radiation, a very powerful X-ray source. This technique allows us to obtain a perfect digital model and very detailed insight views of the old fossil without destroying it.”
Normally, said Stampanoni, the method with which they capture images with the particle accelerator yields high resolution images, albeit on very tiny samples. By adjusting their setup, the team was able to broaden their view while keeping the resolution very high.