Hidden beneath farmland in the central tablelands of New South Wales lies one of Australia’s most extraordinary fossil sites – McGraths Flat. It dates back between 11 million and 16 million years into the Miocene epoch, a time when many of today’s familiar plants and animals evolved.

It is here that palaentologists and geologists from the Australian Museum Research Institute have made remarkable fossil discoveries. Where dust and drought now dominate, a lush rainforest once flourished. In stunning ecological detail, fossils at McGraths Flat reveal this ancient ecosystem.

Strikingly red in appearance, the sedimentary rocks here are composed entirely of goethite – a fine-grained mineral that contains iron. This iron has preserved a range of plants, insects, spiders, fish and feathers with exceptional detail.

Our new study, published in the journal Gondwana Research, shows there’s another reason these rocks are so intriguing. They fundamentally challenge ideas about where well-preserved fossil sites on Earth can be found, and why.

Traditionally, the most exceptionally well-preserved fossil sites are from rocks dominated by shale, sandstone, limestone, or volcanic ash.

Consider

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