Australasian Science: Australia's authority on science since 1938

Platypus-Like Fish Fossil Found at Ancient Reef Site

Palaeontologists from Flinders University and the Australian National University have discovered a remarkable ancient fish fossil with a long snout that resembles a platypus bill.

The fossil, named Brindabellaspis after the nearby Brindabella Ranges, belongs to an extinct group of fish called the placoderms. It was first found in 1980 in limestone around Lake Burrinjuck in NSW, an area containing some of the world’s earliest known reef fish fauna. The researchers have reconstructed two of the ancient fossils and discovered that the fish had a long bill extending out in front of its eyes.

“This was one strange-looking fish,” said study author Benedict King. “The eyes were on top of the head, and the nostrils came out of the eye sockets. There was this long snout at the front, and the jaws were positioned very far forward.” The fossil also revealed a unique sensory system on the snout that turned out to be a modified form of the pressure sensor system found in other fish.

“We suspect that this animal was a bottom-dweller,” says co-author Prof John Long of Flinders University. “We imagine it used the bill to search for prey, somewhat like a platypus, while the eyes on top of the head looked out for danger from above.”

Dr Gavin Young of ANU found the first two specimens, but the sensitive snout region was missing. “When we saw the dense sensory tubes on another broken snout, we immediately thought of the local platypus,” he says.

Long says the fossil re-examination filled in the gaps, “but not in a way anyone expected. Despite this being one of the earliest well-known ecosystems including many species of fish, the inhabitants of this ancient reef were clearly not in any way primitive. The new findings show that they were highly adapted and specialised in their own right.”

A string of recent discoveries from the Lake Burrinjuck fossil site have included evidence for electroreception, new information on the evolution of jaws, and a tiny skull that bridges the gap between the two major divisions of the bony fish.

The discovery has been published in Royal Society Open Science (http://dx.doi.org/10.1098/rsos.180094).