A Millennium Falcon from the Cambrian

A prehistoric marine predator that lived half a billion years ago has been named after the Millennium Falcon starship from Star Wars.

The new species – Cambroraster falcatus – was described from fossils pressed between sheets of rock in the famous Burgess Shale formation in the Canadian Rockies.

Discovered in 1909, the Burgess Shale dates back to the middle Cambrian, some 506 million years ago when a cornucopia of multicellular lifeforms blossomed into existence.

Like similar formations, it is unique in having preserved numerous soft-bodied fossils from this time, many of which have no known living relatives.    

Hundreds of Cambroraster fossils have been unearthed over recent years in the northern Kootenay National Park, which lies roughly 40 kilometres south of the original Burgess Shale site.

Palaeontologists Joe Moysiuk and Jean-Bernard Caron, both from the Royal Ontario Museum and the University of Toronto, used more than one hundred of these fossils to piece together a detailed description of the new beast.

“The sheer abundance of this animal is extraordinary,” says Caron. “Over the past few summers we found hundreds of specimens, sometimes with dozens of individuals covering single rock slabs.”

Cambroraster’s large head is covered by a hard carapace, similar in shape to the shell of a horseshoe crab. Flaps along the side of its body would have helped the marine creature propel itself through the water.

Its circular tooth-lined mouth is adorned by a fancy moustache of rake-shaped feeding appendages. (Cambro refers to Cambrian; raster, to these rake-like claws).

“We think Cambroraster may have used these claws to sift through sediment, trapping buried prey in the net-like array of hooked spines,” says Caron.

All told, Cambroraster grew up to 30 centimetres in length – massive by the standards of its day.

“Most animals living during the Cambrian Period were smaller than your little finger,” says Moysiuk, who led the study.

Cambroraster belongs to a group of organisms called radiodonts, all of which have round, toothy smiles and are distant relatives of today’s exoskeleton-wielding arthropods – crustaceans, insects, spiders and the like.

“The radiodont fossil record is very sparse; typically, we only find scattered bits and pieces,” says Caron.

“The large number of parts and unusually complete fossils preserved at the same place are a real coup, as they help us to better understand what these animals looked like and how they lived,” he says.

Cambroraster doesn’t just bear a passing resemblance to horseshoe crabs (and the Millennium Falcon) – it probably foraged in a similar way, too, scooting along the sea floor and using its carapace to plough through sediment as it fed.

“This represents a remarkable case of evolutionary convergence in these radiodonts,” says Moysiuk.

The work is published in the Proceedings of the Royal Society B.

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