[ad_1]
Grass and undersized trees dominate the Central Tablelands, hundreds of kilometers northwest of Sydney, Australia today. But scientists have recently discovered that some of the region’s rusty rocks hide traces of the lush rainforest that covered the area during the Miocene Period, 15 million years ago.
The McGraths Flat site isn’t Australia’s only Miocene deposit, but these new fossils are a paleontological boon because of their excellent preservation. In the past three years, paleontologists have dug up flowers, insects, and even a bird’s wispy feathers.
inventions of scientists Published Friday in the journal Science AdvancesHelp reconstruct Australia’s Miocene rainforest in extensive detail, and the site “opens up a whole new field of exploration for Australian paleontology,” said Scott Hocknull, a paleontologist at the Queensland Museum who was not involved in the research.
Fifteen million years ago, a river running through the forest left behind an oxbow lake (known as a billabong in Australia) at McGraths Flat. This stagnant pool, nearly devoid of oxygen, kept scavengers away and allowed plant material and animal carcasses to accumulate. Iron-rich runoff from nearby basalt mountains seeped into the billabong, while the pool’s low pH caused iron to precipitate and coat organic material. As a result, the fossils at McGraths Flat are preserved in a dense, iron-rich rock known as goethite.
Dr. This fossilization method is rare, Hocknull said. Because quality fossils are rarely found in igneous rocks, paleontologists often overlook them. But fossils from McGraths Flat show that goethite, common in Australia, may yield remarkable fossils.
Dr. “There’s no shortage of Gothites,” Hocknull said. “We are actually a rusting country.”
Because of their iron-colored origins, many of the fossils at McGraths Flat shimmer with a metallic sheen. In addition to intact plants, goethite crawls with fossilized insects. When the researchers separated the brick-colored stone slabs, they discovered a miniature zoo of giant cicadas, dragonflies and parasitic wasps. And many of them have been remarkably preserved – some ancient flies bear detailed imprints of their compound eyes.
The site has also yielded more than a dozen archaic arachnids. While insects have robust exoskeletons, Michael Frese, a virologist and paleontologist at the University of Canberra and co-author of the study, likens spiders to “squishy bags of fluid.” As a result, Australia’s spider fossil record was virtually non-existent before McGraths Flat.
According to Matthew McCurry, curator of paleontology at the Australian Museum and lead author of the study, the fossils are so well preserved that paleontologists have been able to observe relationships between species – something that is often difficult to isolate from fossil sites. For example, the team observed parasites attached to the tail of a fish and a nematode infiltrating a long-horned beetle.
Dr. Frese used an electron microscope and microphotography techniques to study the inhabitants of the rainforest. Dr. While viewing a fossilized sawfly, Frese discovered a clump of pollen on the bee-like insect’s head.
Dr. “We can tell which flower this sawfly visited before it fell into the water and saw its untimely end,” Frese said. “This would not have been possible if the quality of protection was not so high.”
Pollen also revealed that rainforests are surrounded by drier environments, making McGraths Flat more likely to represent a remnant piece of what was once a larger forest. Dr. According to McCurry, this makes sense given the climatic trends of the Miocene.
Australia was drifting north, away from Antarctica, when these beetles scurried around the iron-spotted billabong. As it traveled, its climate dried up greatly, causing the rainforest to retreat and widespread extinction.
The researchers believe McGraths Flat offers an intimate look at how this dramatic climate shift is affecting certain species in the rainforest ecosystem. For example, some insects found in McGraths Flat have withstood drier conditions, while others are now only found in the remaining rainforests of northern Australia.
Dr. “By studying these fossil ecosystems, we can see which species are better able to adapt to these changes,” McCurry said. “We can potentially predict which ones are most at risk for future changes.”
Dr. Frese said McGraths Flat is particularly useful for reconstructing ancient ecosystems because of the diversity of species it preserves.
Dr. “Our site is different because it’s all small fossils, but in the end, I think it will tell us more about what’s going on in the ecosystem,” Frese said. “You don’t need to find a one-ton terror bird to tell this story.”
[ad_2]
Source link