If you are going to take a cool, relaxing dip in the ocean, it’s really best just to take your chances and not consider the many other species that are swimming and swirling around in the water beside and beneath you. While you might be worrying about stepping on a stingray, getting stung by a jellyfish, or chomped on by Jaws, there are so many other things you’ve never even considered—and that’s probably good. But while the terrors of the deep may serve as reason to send you running out of the surf, they can also take on a much more benevolent—and educational—form. Especially when we go back a few years—or say, maybe 400 million of them.
Some lucky scientists have been studying an ancient fish fossil found in Australia which is actually helping us to learn more about the evolution of the human body as well. The current subject of fascination at the Australian National University (ANU) and Queensland Museum is teeth. And the secret to how they progressed in human form may be found in the fossil of the Buchanosteus, a placoderm that is certainly long extinct.
“We have used CT scanning facilities to investigate the internal structure of very fragile fossil skulls and braincases that have been acid-etched from limestone rock,” said Gavin Young from ANU.
This allowed them to see how the jaw moved, as well as investigating the internal tissue showing ‘tooth-like denticles.’ The goal was to establish how teeth evolved in animals, and humans. And this has been a major scientific question, explains Yuzhi Hu, a PhD candidate at ANU.
“We are researching this question using new evidence from an exceptionally preserved fossil fish about 400 million years old,” said Hu.
Due to 3D printing, scientists now have a much better way to study a specific and detailed structure such as the jaw and teeth of such a creature. The team discovered that the Buchanosteus jaw and dental pattern is unlike anything alive today, and they were also able to show evidence which disputes previous claims that these ancient fish actually had real teeth.
“Placoderms have been a common focus in the question of tooth origins,” said Carole Burrow from Queensland Museum. “Our team has been able to examine the gnathal plates of placoderms from the Early Devonian period, and compare their internal and external structure with those of younger placoderms as well as with the true teeth in other jawed fishes.”
The researchers outlined their findings in ‘Placoderms and the evolutionary origin of teeth: a comment on Rücklin & Donoghue,’ disputing results of previous research which suggested that the extinct placoderms had real teeth.
“A key question is whether these gnathal plates were modified from external dermal bones, or had ‘denticles’ representing true teeth with pulp cavities. The recent contribution by Rücklin & Donoghue confuses this issue, because their claimed ‘anterior supragnathal’ (ASG) of the placoderm Romundina stellina shows no evidence that it came from the oral cavity, and is more likely an external dermal element,” state the researchers in their paper. “Also, the tissue identified as enameloid is not birefringent and thus not enameloid. Their inferences about growth of toothplates, phylogenetic loss of enameloid, and independent development of teeth and jaws, based on the structure of this plate, are therefore invalid.”
Through their digital study as well as being able to study 3D models, the researchers stated that they found no ‘orthodentine,’ as would be typical in a tooth. With this, they concluded that there indeed were not teeth, but only the tubercles. There is also a reply to this paper, which you can read here, as the scientists bat the subject of what really constitutes ancient fish teeth back and forth.
And despite the outcome of the research—or how the ongoing argument regarding fossilized dental patterns ensues—one thing is for certain here: we are seeing true evidence of the benefits provided to science by 3D printing, as the scientists were allowed to re-create fossils affordably and study them comprehensively, while saving the originals from further degradation. This is a growing trend today in both labs and museums, which should lend many other great successes to research as scientists continue to share—and discuss subjects such as these ancient fossils at hand. What do you think of this study? Let’s talk about it over in the 3D Printed Fish Fossil forum at 3DPB.com.[Source: Deccan Chronicle]