15-Million-Year-Old Fish Fossils Were Discovered In Australia, And Paleontologists Can See What They Ate
Discovered in Australia, these fossilized fish are so well-preserved that paleontologists can see what they last ate roughly 15 million years ago. The fish belong to a newly identified species called Ferruaspis brocksi.
F. brocksi was a small fish that lived in freshwater lakes in what is now central New South Wales. Today, the region is mostly farmland, but during the Miocene epoch, it was a lush, temperate rainforest.
While exploring a research site called McGraths Flat near the town of Gulgong, a team of paleontologists stumbled upon several intact F. brocksi fossils.
At the site, one of the researchers decided to split open a rock. That’s when he found a fossilized fish with soft tissue and an intact skeleton.
However, the researchers did not recognize the creature. As they continued looking around, they discovered a few dozen additional fossils of the same type of fish.
They were so well-preserved that the remains of their last meals could be seen. Before they died, the fish had eaten insects, bivalves, and phantom midge larvae.
One of them even had a parasite stuck to its tail. It was a juvenile freshwater mussel known as a glochidium. The fossilized fish were entombed in a mineral called goethite, which contains a lot of iron. This was a surprise because the researchers did not realize that the mineral could preserve fossils so well.
In the future, paleontologists might want to take a closer look at goethite rocks. The mineral inspired part of the new species’ scientific name, Ferruaspis brocksi.
“Ferru” comes from the Latin word for iron, while “brocksi” is in honor of Jochen Brocks, an earth scientist from the Australian National University, who discovered the fossils.
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After bringing the fossilized fish back to the lab, the researchers put them under a scanning electron microscope, revealing the remnants of melanosomes, which are cells that produce the pigment melanin.
The cells indicate that F. brocksi had a light-colored stomach, a darker-colored back, and two lateral stripes on its side.
It marks the first time that fossilized melanosomes have been used to determine the color pattern of a fish that has been extinct for thousands of years.
F. brocksi belongs to the Osmeriformes order, a group of ray-finned freshwater fish that includes the Australian grayling and the Australian smelt. This is the first time that a fossilized Osmeriformes fish has been found in the country.
Now, the research team hopes that the new discovery will shed some light on the history and lineage of the Osmeriformes group.
It may also provide insights into ancient Australian ecosystems during the Miocene, when the continent’s climate was changing.
The details of the new findings were published in the Journal of Vertebrate Paleontology.
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