Canberra, Mar 19 (UNI) The discovery of new fish species that inhabited Australia's freshwater lakes and rivers 15 million years ago provides insights into the evolution of freshwater fish species and Australia's ancient ecosystems, scientists said on Wednesday.

The newly identified fish species was named after Prof. Jochen Brocks from the Australian National University (ANU), who played a key role in its discovery, according to a news release of the ANU Research School of Earth Sciences.

The fossil of the ancient fish, named Ferruaspis brocksi, was found at McGraths Flat, a fossil site near Gulgong, New South Wales. The name derives from "ferru" (Latin for iron) due to its preservation in iron-rich rock and "brocksi" after Prof. Brocks.

It is the first fossil of an Australian Smelt species, helping to pinpoint when this group arrived in Australia and how they evolved, said the study's lead author Matthew McCurry from the Australian Museum and the University of New South Wales Sydney.

The fossil's stomach contents were so well preserved that researchers identified its diet, mainly small phantom midge larvae. They also discovered a juvenile freshwater mussel attached to the fish's tails or gills, "to hitch rides up and down streams," McCurry said.

Another exciting aspect, scientists reconstructed the fish's color pattern using fossilized melanosomes, a method previously applied to ancient bird feathers but never to fish, said Michael Frese from the University of Canberra and the Commonwealth Scientific and Industrial Research Organization, Australia's national science agency.

"The fish was darker on its dorsal surface, lighter in color on its belly and had two lateral stripes running along its side," Frese said.

The McGraths Flat fossil site offers a glimpse into a once-temperate rainforest teeming with life between 11 and 16 million years ago, according to the study, published in the Journal of Vertebrate Palaeontology.

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