Predator with compound eyes on stalks terrorised the Cambrian oceans

Compound eyes gave Anomalocaris, the ancestor of modern insects, a huge advantage when locating its prey
  • The Guardian,
  • Jump to comments ()
Super predator Anomalocaris View larger picture
An artist's impression of Anomalocaris. Each of its compound eyes contained more than 16,000 lenses. Photograph: Katrina Kenny/University of Adelaide

The remains of a pair of ancient compound eyes that belonged to the world's first super predator have been discovered by fossil hunters in Australia.

Anomalocaris was a soft-bodied marine animal that patrolled the oceans more than half a billion years ago. Adults grew to a metre long and had eyes on stalks.

The creature also had grasping claws and teeth-like serrations in its mouth that it used to capture and feed on other marine animals. The fossilised excrement of the predator suggests it may have crunched up trilobites, which were up to 25cm long.

Researchers uncovered the fossilised eyes in 515m-year-old rock layers on Kangaroo island, in South Australia. Alongside, they found remains of the animal's claws and the swimming flaps that ran down the length of its body.

Each eye was about three centimetres across and contained more than 16,000 separate lenses, enough to give the creature remarkable vision to support its predatory lifestyle.

The ability to spot prey from far away would have influenced the evolutionary arms race that played out in the Cambrian era, when animal life became extraordinarily diverse.

"These huge, sophisticated, eyes would give animals a tremendous advantage at locating prey," said Gregory Edgecombe, a co-author on the study, at the Natural History Museum in London.

Previous discoveries of Anomalocaris from the Burgess shale, in Canada, and Chengjiang, in China, have included fully articulated bodies, but none has captured the exquisite details of the compound eyes before.

Anomalocaris sits near the foot of the arthropod family tree, making it a primitive ancestor of modern insects and crustaceans. The appearance of compound eyes so early on shows they evolved before other characteristic features such as hardened outer skeletons and jointed walking legs, said John Paterson, who led the study at the University of New England, New South Wales. Details of the fossils are reported in the journal, Nature.

Anomalocaris was alive at a time when the land mass – what is now Australia – straddled the equator. So the ocean temperatures in the region would probably have been tropical. There would have been a menagerie of marine organisms in the oceans, including trilobites, worms, sea slugs and sponges.

"What this discovery tells us is that the origin of compound eyes can almost be traced back to the last common ancestor of all arthropods," Paterson said. "What I would love to find next are definitive compound eyes in an animal considered to be even more primitive than Anomalocaris, like the bizarre, five-eyed creature called Opabinia, from the Burgess shale."

Today's best video

Today in pictures

Super predator Anomalocaris

Artist's impression of Anomalocaris, a metre-long top predator that hunted in the Cambrian oceans. Fossilised remains suggest that compound eyes evolved before hardened exoskeletons and provide further evidence that the creatures are related to arthropods, including insects and crustaceans. Photograph: Katrina Kenny/University of Adelaide