Credit...Michael Frese
The New York Times Trilobites column has a story about the discovery of a fossil rain forest in the outback of Australia. The deposit is located hundreds of miles northwest of Sydney in a place called McGraths Flat. The fossils date to the Miocene Epoch when Australia was much wetter. There's flowers, insects, spiders, and even a feather. The discovery is documented in a paper called "A Lagerstätte from Australia provides insight into the nature of Miocene mesic ecosystems" published in the journal Science Advances.
Fifteen million years ago, a river carved through the jungle, leaving an oxbow lake (known as a billabong in Australia) in its wake at McGraths Flat. Nearly devoid of oxygen, this stagnant pool kept scavengers at bay, allowing plant material and animal carcasses to accumulate. As iron-rich runoff from nearby basalt mountains seeped into the billabong, the pool’s low pH caused the iron to precipitate and encase the organic material. As a result, the fossils at McGraths Flat are preserved in a dense, iron-rich mineral known as goethite.
This method of fossilization is uncommon, Dr. Hocknull said. Because quality fossils are rarely found in iron deposits, paleontologists often overlook them. However, the fossils from McGraths Flat illustrate that goethite, which is common in Australia, can yield remarkable fossils.
“There’s no shortage of goethite,” Dr. Hocknull said. “We’re essentially a rusting country.”
