Scientists uncover 15 million year old fossilized fish in Australia

Canberra, Mar 19 ,2025 : A newly discovered fish species that thrived in Australia’s freshwater lakes and rivers around 15 million years ago is shedding light on the evolution of freshwater fish and the country’s ancient ecosystems, scientists revealed on Wednesday.

The ancient fish species has been named Ferruaspis brocksi, in honor of Prof. Jochen Brocks from the Australian National University (ANU), who significantly contributed to the research, according to a news release from the ANU Research School of Earth Sciences.

The fossil was unearthed at McGraths Flat, a well-preserved fossil site near Gulgong, New South Wales. The name “Ferruaspis” is derived from the Latin word “ferru,” meaning iron, referencing the iron-rich rock in which the fossil was preserved, while “brocksi” pays tribute to Prof. Brocks.

According to Matthew McCurry, the study’s lead author from the Australian Museum and the University of New South Wales Sydney, this is the first fossil evidence of an Australian Smelt species, offering key insights into when these fish first arrived in the region and how they evolved over time.

One of the most remarkable aspects of the discovery is the exceptional preservation of the fish’s stomach contents, which allowed researchers to determine its diet—mainly consisting of small phantom midge larvae. Additionally, scientists found a juvenile freshwater mussel attached to the fish’s tail or gills, suggesting that the mussel may have used the fish as a means of transportation up and down waterways.

Another groundbreaking aspect of the research is the reconstruction of the fish’s color patterns. Michael Frese, from the University of Canberra and the Commonwealth Scientific and Industrial Research Organization (CSIRO), stated that fossilized melanosomes—tiny pigment-containing structures—were used to determine the fish’s coloration, a technique previously applied to ancient bird feathers but never before to fish fossils.

“The fish exhibited a darker shade on its dorsal side, a lighter belly, and two lateral stripes running along its body,” Frese explained.

The McGraths Flat fossil site provides an extraordinary look into an ancient temperate rainforest ecosystem, which flourished between 11 and 16 million years ago. The findings, published in the Journal of Vertebrate Paleontology, mark a significant step in understanding the biodiversity of prehistoric Australia and how its aquatic life evolved over millions of years.