16-Million-Year-Old Rare Fish Fossils' 'Detailed Preservation' Helped Scientists Determine Its Last Meal
Fossils are a great way to determine the reality of past ecosystems. Oftentimes, experts have to struggle a lot to get a clear picture from these fossils, as several of them withstand a lot of damage over time. Researchers were elated when they didn't face this issue while examining certain fish fossils found in Australia, stated CNN. Findings regarding these fossils have been published in the Journal of Vertebrate Paleontology.
In 2024, researchers announced the discovery of these fish fossils and named them Ferruaspis brocksi. The remains were spotted at the McGraths Flat site in central New South Wales. Multiple fossils of F. Brocksi were detected inside goethite. The iron-rich goethite protected the remains since the Miocene Epoch. The fossils were so exceptionally preserved that experts were able to analyze the 16-million-year-old species' structural features in detail. The team was astounded that they were even able to look into the fish's soft tissue, stomach, and coloration patterns.
Fossils of such quality are extremely hard to come by, as per researchers associated with the study. "Every time I have a detailed look at a fossil from McGraths Flat, I am amazed by its detailed preservation," study coauthor Dr. Michael Frese, associate professor and virologist at the University of Canberra, said. "It’s very surprising, (and) it’s extremely rare to be able to tell the colour of a fossil fish like this."
Researchers have determined that the ancient fish belonged to the Osmeriformes family. This family consists of modern-day graylings and smelts. Before this discovery, researchers did not have much information regarding the arrival of smelts in Australia. However, the uncovering of F. Brocksi could potentially give them new insights regarding the ancient ecosystem in place in the region and also provide answers to such queries. "While this study is focused on one species of fish, it is part of a broader ecosystem that we are piecing together by excavating fossils from the site," Frese said.
Paleontologists used high-powered microscopes to look into the stomach and intestinal tracts of F. Brocksi. The observation helped them figure out that this kind of fish primarily ate various types of phantom midge larvae and insect wings. "Knowing their diet helps us start to paint a picture of food chains and food webs in the original environments," said Dr. Anthony Martin, a professor of practice in the department of environmental sciences at Emory University in Atlanta, who was not involved in the study.
Along with the food remains, researchers also noted the feeding schedule of this species in their analysis. "Many extant species of Chaoborus (phantom midge larvae) do not occur in lakes with fishes, and those that do co-exist with fishes often conduct a diurnal migration to avoid predatory fishes during the daytime," Frese said. "As most Chaoborus larvae spent most of the day in the sediment, hiding from pelagic predators, F. brocksi would likely have preyed on Chaoborus at night."
Researchers spotted melanophores, or pigmented cells, in these remains. Through these cells, they were able to figure out the coloration pattern of this kind of fish. The cells indicated that the fish was darker at the top, while lighter at its stomach region. The study further claimed that there were two stripes running across the body of this fish.