Weird platypus-fish lived on ancient reef

Palaeontologists have pieced together a revealing picture of a strange platypus-like fish.
Palaeontologists have pieced together a revealing picture of a strange platypus-like fish.

Palaeontologists have reconstructed an ancient Australian fish that swam on the sea floor like a stingray and had the long bill of a platypus.

Fossils that date back 400 million years have allowed scientists to piece together a revealing picture of the strange fish, which had nostrils coming from its eye sockets and a long bill or snout with jaws.

It is named Brindabellaspis after the Brindabella Range near Canberra and belongs to an extinct group of armoured prehistoric fish known as placoderms.

Scientists from the Australian National University and Flinders University have dated the fossils to the early Devonian period, more than 175 million years before the first dinosaurs.

They were discovered in limestone around the Lake Burrinjuck dam at the head of the Murrumbidgee River, north of The Brindabellas in NSW.

The area contains some of the earliest reef fish fauna and the world's finest example of an ancient tropical coral reef.

It was a thriving biodiversity hotspot that rivals the Great Barrier Reef of today.

Palaeobiologist Dr Gavin Young, who discovered the first fossils in 1969, says Brindabellaspis is the strangest of the more than 70 species of fish found in the ancient ecosystem.

"This thing is really weird, it doesn't really fit in anywhere," he told AAP.

It's believed the fish was a bottom dweller, which used its snout or bill to search for prey.

Dr Young said the fossil had another surprise, a unique sensory system on the snout that turned out to be a modified form of the pressure sensor system found in other fish.

"It has a very weird and unexpected skull shape with a long snout and the possible capacity to use electrical reception to find animals in the soft mud at the sea bottom," he said.

When the team spotted the dense sensory tubes in the skull they immediately thought of the platypus, he said.

"(However) there are no platypuses swimming around on the Great Barrier Reef today," he said.

"The animals that do that are the sharks and stingrays. A ray can swim over a sandy bottom and detect prey hidden in the mud by using electro-reception."

The paper was published in the journal Royal Society Open Science on Wednesday.

Australian Associated Press