Jawless creature had world’s sharpest teeth

By Jessica Passananti 28 March 2012
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A jawless, eel-like creature had the sharpest teeth ever known, according to a recent discovery of fossil remains.

THE SHARPEST TEETH EVER discovered belong to a surprising animal: a jawless, eel-like vertebrate that lived from 500-200 million years ago.

Scientists suspect the conodont was one of the first vertebrates ever to develop teeth. Despite having no jaw, its razor sharp chompers – which taper down to the width of one-twentieth of a human hair – were capable of slicing with great force for their size.

“[The discovery] shows that even the earliest vertebrate teeth we know of were extremely well-adapted for capturing and breaking down food,” says evolutionary biologist Dr Alistair Evans from Monash University in Melbourne. 

Razor sharp teeth from a common fossil

Alistair and his team discovered the fossil teeth in Ontario, Canada. Conodonts are a common fossil from the Precambrian eon and are found all over the world, including Australia. Their extinction – perplexing to scientists because of how common they were – still remains a mystery.

These 1-2cm fish managed surprisingly well for their  size. Conodonts were able to bite through prey much bigger than themselves without applying much pressure. “It’s almost like a set of needles pointing out of the tooth,” says Alistair.

The discovery gives insight into the evolution of mammalian teeth too, he says. “We can see a lot of similarities in their shape [in mammals and conodonts]… This shows us how general these characteristics are for teeth as a whole.”

Fine teeth compensated for little bite force

Humans developed less efficient, blunter teeth because they had jaws to apply pressure to food morsels. Conodonts, on the other hand, could only apply tiny forces since their teeth were directly embedded in cartilage, rather than jawbones. “Sharp teeth would quickly break and wear down under the pounding they would suffer with those large forces,” says lead author Dr David Jones from the University of Bristol in England.

Fossil records suggest that conodonts were some of the earliest known vertebrates (animals with a backbone), so they may have been among the first to develop functioning teeth. But things may have become tough for conodonts in the latter part of their reign, comments Professor David Bellwood a marine biologist at James Cook University in Queensland.  As new creatures evolved, and “their prey became harder…they lost out to other [newer species] with brute force and blunt teeth.”

“It is an interesting insight into the costs and consequences of evolutionary trade-offs. We can see the same trade-offs today in the plethora of teeth [found] in coral reef fishes – although none can afford, or need to be, as sharp as their ancient conodont counterparts,” says David. “I guess the blunt and dull inherited the Earth.”

The findings are published in the Proceedings of the Royal Society B journal.