Discovered in southeastern Australia, the fossils—strewn over an area no bigger than half a football field—contain one of the most astonishing records ever found of life in an ancient rainforest
Some 16 miles outside of the town of Gulgong in southeastern Australia, landowner Nigel McGrath spent one day a few years ago working a particularly tough part of his fields. The patch of land was strewn with heavy, iron-rich rocks that menaced his farm equipment, so McGrath had to haul the loose blocks into piles by hand. That’s when he noticed them: immaculately preserved fossil leaves, tucked into the rocks like pressings in a book of stone.
“The exceptional quality and quantity of the material discovered is remarkable, as is the biological and ecological information extracted and presented,” says University of New South Wales paleontologistThe McGraths Flat fossils even contain snapshots of life in action. One sawfly’s head was covered in pollen, presumably after feasting on a flower’s nectar. One fish’s tail held a passenger: the parasitic larva of a mussel, which subsisted on the fish’s slime as it hitched a ride upriver.
Frese adds that the unusual type of fossilization makes the McGraths Flat fossils especially easy to analyze with scanning electron microscopes , some of the most powerful microscopes available. Generally, samples being put under an SEM have to be coated in thin layers of gold or platinum, which can restrict future research on those samples.
The team has some reason to think that the lake’s goethite cycle may have been caused by seasonal monsoons. Of the hundreds of fossil flowers found at McGraths Flat so far, most of them died before they had bloomed, suggesting that the burials occurred during a consistent time of year. The team also has many fossils of insects that, in modern ecosystems, are seen only in the spring and summer.
During the early and middle Miocene, atmospheric CO2 levels were roughly 400 to 500 parts per million, similar to estimates of near-future CO2 levels brought on by human activity. The Miocene also saw sustained warming periods, such as the mid-Miocene climatic optimum 17 to 14 million years ago, which may have overlapped with the slice of time recorded at the McGraths Flat site.