Paleontologists from the Australian Museum Research Institute, the University of New South Wales, the University of Canberra and CSIRO have described a new species of osmeriform fish from the fossilized remains found in New South Wales, Australia; preserved stomach contents of the fish indicate an opportunistic benthopelagic diet, evidenced by the remains of numerous phantom midge larvae, two insect wings, and a bivalve.
Habitus and fin positions of Ferruaspis brocksi. Scale bar – 8 mm. Image credit: McCurry et al., doi: 10.1080/02724634.2024.2445684.
The newly-described fish species lived during the Miocence epoch some 15 million years ago, and belonged to the order Osmeriformes (freshwater smelts and their allies).
Named after Australian National University’s Professor Jochen Brocks, Ferruaspis brocksi is the first fossil freshwater smelt to be found in Australia.
“I am very proud to have this world-first discovery named after me,” Professor Brocks said.
“This discovery opens new avenues for understanding the evolutionary history of Australia’s freshwater fish species and ancient ecosystems.”
Professor Brocks discovered several fossils of Ferruaspis brocksi at the McGraths Flat fossil site near Gulgong in New South Wales.
“Before this fossil discovery, scientists lacked concrete evidence to pinpoint when this group of fish arrived in Australia and how they evolved over time,” said Dr. Matthew McCurry, from the Australian Museum Research Institute and the University of New South Wales.
“Ferruaspis brocksi is the first fossil freshwater Australian smelt to be found in Australia.”
“The discovery of the 15 million-year-old freshwater fish fossil offers us an unprecedented opportunity to understand Australia’s ancient ecosystems and the evolution of its fish species.”
“This fossil is part of the Osmeriformes fish family — a diverse group of fish species within Australia that includes species like the Australian grayling and the Australian smelt.”
“But, without fossils it has been hard for us to tell exactly when the group arrived in Australia and whether they changed at all through time.”
The well-preserved stomach contents of Ferruaspis brocksi provide the paleontologists with a glimpse into the behavior of these ancient species.
“We now know that Ferruaspis brocksi fed on a range of invertebrates, but the most common prey was small phantom midge larvae,” Dr. McCurry said.
“One of the fossils even shows a parasite attached to the tail of the fish. It’s a juvenile freshwater musselcalled a glochidium.”
“These juvenile musselsattach themselves to the gills or tails of fish to hitch rides up and down streams.”
“This little fish is one of the most beautiful fossils I’ve found at McGrath Flat, and finding the first vertebrate among the abundant plant and insect fossils was a real surprise,” Professor Brocks said.
One of the most exciting aspects of the work was that they could tell the color of Ferruaspis brocksi.
“The fish was darker on its dorsal surface, lighter in colour on its belly and had two lateral stripes running along its side,” said Dr. Michael Frese, a paleontologist at the University of Canberra and CSIRO.
“Using a powerful microscope, we were able to see tiny color-producing structures known as melanosomes.”
“Fossilized melanosomes have previously enabled paleontologists to reconstruct the color of feathers, but melanosomes have never been used to reconstruction of the color pattern of a long extinct fish species.”
A paper on the findings was published this week in the Journal of Vertebrate Palaeontology.
_____
Matthew R. McCurry et al. The paleobiology of a new osmeriform fish species from Australia. Journal of Vertebrate Palaeontology, published online March 17, 2025; doi: 10.1080/02724634.2024.2445684
