This is a particularly exciting find because not only does this fossil provide a vital link between two strikingly different groups, but it also has a bearing on the early evolution of a major phylum - the deuterostomes.
-Professor Simon Conway Morris
The identification of curiously-shaped fossil of a marine worm found in Canada as a new species has pushed the record of the group to which it belongs back by 200 million years and helped to solve an evolutionary puzzle.
The research, which is published online by the journal Nature, was carried out by a team of scientists from Canada and the UK. They examined numerous specimens, some of which were collected more than a century ago and are now held in the Smithsonian Institution (Washington, DC), along with new material recently collected by the Royal Ontario Museum (Toronto).
The newly-identified species comes from the Burgess Shale beds, located in Yoho National Park in the Rocky Mountains of British Columbia, an area that boasts one of the world’s most important fossil-rich deposits. The fossil shows that the acorn worm group – members of which thrive today in fine sands and mud – was living 505 million years ago when the mountainside shale in which it was discovered was under the ocean.
Named Spartobranchus tenuis, the species was previously unknown to science and its survival as a fossil is remarkable. It belongs to a group of animals known as enteropneusts – spaghetti-shaped creatures with soft bodies which in normal circumstances deteriorate rapidly – and dates from the Cambrian period.
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Image: Spartobranchus tenuis reconstruction by Marianne Collins
Credit: Caron, Cameron and Conway Morris
Reproduced courtesy of the University of Cambridge
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