Imagine a lush and vibrant rainforest teeming with life, with various insects crawling and flying around, and abundant aquatic fauna. This is what the now cool, temperate Central Tablelands in southwestern Australia would have looked like around 15 million years ago.This was confirmed by a spectacular recent discovery at the McGrath Flat fossil site near Gulgong in New South Wales, Australia. The site is classified as a "Lagersttte" a location that contains fossils of exceptional quality with remarkable detail.Professor Jochen Brocks, a researcher from the Australian National University, not only discovered a new ancient fish species, Ferruaspis brocksi (named after him), but also made a remarkable find. The fossils extraordinary preservation offers a wealth of information about the species, allowing paleobiologists to reconstruct the flora and fauna of the past. The findings were published by the Australian Museum Research Institute, Sydney, in the Journal of Vertebrate Paleontology.Ancient Fish FossilFerruaspis brocksi is the first fossil freshwater Australian Smelt to be found in Australia, said study lead author Matthew R. McCurry from the Australian Museum and UNSW Sydney in a press release.The ancient species belongs to the Osmeriformes fish family, a crucial group of fish in freshwater ecosystems in Australia and New Zealand. However, their fossil record was poorly represented in these countries, making it difficult to pinpoint their arrival in Australia and understand their evolution.The fossils of F. brocksi, found at the popular McGrath Flat site, are embedded and mineralized in iron-rich rock, which enabled the unusual degree of preservation of this fish, living between 11 million years and 16 million years ago. The preservation even reveals details such as the contents of its stomach and remnants of its color.Reconstructing Behavior and AppearanceThe exceptionally well-preserved stomach contents of the fossilized fish have allowed researchers to reconstruct its behavior, such as its opportunistic diet while living on both the seafloor and in open waters.We now know that F. brocksi fed on a range of invertebrates, but the most common prey was small phantom midge larvae. One of the fossils even shows a parasite attached to the tail of the fish. Its a juvenile freshwater mussel called glochidium. These juvenile mussels attach themselves to the gills or tails of fish to hitch rides up and down streams, said McCurry in the release. Another exciting aspect of this discovery is that researchers have been able to determine the fishs color. Michael Frese from the University of Canberra and CSIRO, Australias national science agency, described the fish as "darker on its dorsal surface, lighter in color on its belly, with two lateral stripes running along its side," in the news release.He added, 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 before been used to reconstruct the color pattern of a long-extinct fish species.Excitement of PaleontologyThis little fish is one of the most beautiful fossils Ive found at McGrath Flat, and discovering the first vertebrate among the abundant plant and insect fossils was a real surprise, said Brocks in the press release, highlighting the excitement of paleontology.Based on where the fossils were found, its likely that the species lived its entire life in freshwater. This contrasts with currently existing Osmeriformes species and underscores how specimens with preserved soft tissues can provide valuable insights into the evolutionary history of Australias freshwater fish species and ancient ecosystems.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Encyclopedia of Geology: LagersttteJournal of Vertebrate Paleontology: The paleobiology of a new osmeriform fish species from AustraliaHaving worked as a biomedical research assistant in labs across three countries, Jenny excels at translating complex scientific concepts ranging from medical breakthroughs and pharmacological discoveries to the latest in nutrition into engaging, accessible content. Her interests extend to topics such as human evolution, psychology, and quirky animal stories. When shes not immersed in a popular science book, youll find her catching waves or cruising around Vancouver Island on her longboard.