Ancient 'predator fish' with tusks could 'breathe outside of water'

A KILLER fish that lived hundreds of millions of years ago was able to breathe air.

Fossils of the ancient tusked sea beast were found in Australia – in one of the oldest rivers in the world.

This ancient predator used large canines to devour its prey – and adapted to survive a period of 'low oxygen'Credit: Courtesy Journal of Vertebrate Paleontology/Brian Choo & Flinders University

The fish had large canine teeth in addition to tightly packed sharp teeth – and openings at the top of the skull for breathing airCredit: Courtesy of Journal of Vertebrate Paleontology

The 1.3 meter long predator had large and spaced fangs, in addition to a set of tightly packed and sharp teeth.

And it even had four “limbs”, and was seen as the ancestors of modern animals with limbs and backbones.

The fish – known as Harajicadectes zhumini – was special because scientists from Flinders University believe it was able to breathe air.

This breathing process would take place through large openings at the top of its skull.

“It is thought that these spiral structures facilitate air breathing at the surface,” said Dr. Brian Choo, a paleontologist who worked on the study.

“Modern African bichir fish have similar air intake structures at the water surface.”

Dr. Choo studied the most complete specimen of the creature, found in Australia's Finke River.

The river is a goldmine for paleontologists as it is believed to be one of the oldest rivers in the world.

This 750 kilometer long river dates back hundreds of millions of years and has supported many different species over the centuries.

AIR-VOLUTION!

Scientists believe that the adaptation to air breathing seen in this fish occurred when the amount of oxygen in the air was reduced – in the mid-Devonian period.

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It would have allowed the fish to survive better by getting oxygen from multiple sources.

“The ability to supplement gill respiration with atmospheric oxygen likely provided an adaptive advantage,” says Professor John Long, also from Flinders University.

“We found this new form of lobe-finned fish at one of the most remote fossil sites in all of Australia.

“The Harajica Sandstone Member in the Northern Territory, almost 200 km west of Alice Springs, to date from the Middle-Late Devonian, about 380 million years old.”

Scientists found the nearly complete specimen during an expedition to the site in 2016.

But research from more than 50 years of research was used to piece together the story of this particular fish species.

“This fossil showed that all the isolated bits and pieces collected over the years belonged to one new type of ancient fish,” Dr Choo noted.