ANU scientists find ancient fish

Scientists have found the fossilised remains of a previously unknown large marine predator. Source: AAP

A FANG has led to the discovery of a new species of ancient fish that's named after a NSW town.

Gavin Young and a research team were excavating the skeleton of an extinct armoured fish from 360 million-year-old rock near Eden in 2008 when they realised there was an other very interesting fossil at the site.

"As we lifted out the block, we noticed a very large fang, at least four centimetres long," Dr Young said in a statement.

"Armoured fish don't have teeth, so we knew there must be a much larger predator also preserved at the site.

"We uncovered an almost complete skull and shoulder girdle of an enormous lobe-finned fish, with jaws about 48 cm long."

The Australian National University researchers say it is largest fossilised lobe-finned fish skull ever found in rocks of Devonian age and its descendents are believed to have evolved into the first land animals as the boned fins became legs.

When it was alive, Australia and Antarctica were joined in the great southern supercontinent of Gondwana.

"We compared the shape and structure of the preserved bones with about 100 fossil fish species from elsewhere in the world," Dr Young said.

"It turns out that we have not only a species new to science, but also a new genus (genus) of lobe-finned fish, which we have named Edenopteron after the town of Eden."

The species (species) name Edenopteron keithcrooki acknowledges Professor Keith Crook of the former ANU Geology Department.

He supervised student geological mapping on the NSW south coast over several decades, when many of important fossil fish sites were discovered.

This fish has some different features compared to Devonian fish fossils from the Northern Hemisphere, including extra bones in its palate, and strange ornamentation on the scales.

The Eden site is only the fourth place in the world where Devonian fish show these unusual features," Dr Young says.

Preparing the fossil in the ANU laboratory took years - and excavating to see if the rest of its body lies deeper in the rock could take a while too.

"That would be a massive excavation because it would be two to three metres long, but would most definitely be an absolutely spectacular find," Dr Young said.

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