New acquisition: A nest of new spider fossils

The recent discovery of a new and exciting Miocene (11 to 16 million-year-old) fossil site, named McGraths Flat, at Gulgong, central New South Wales, is the cumulation of over three years’ work at the Australian Museum. Many thousands of new specimens from this site have been unearthed and painstakingly prepared, labelled and barcoded for future study by our scientists. The fossils from this area are extremely valuable as they come from a Konservat-Lagerstätten, a special type of geological deposit which preserves plants and animals in immaculate detail, sometimes down to individual cells!

Some of the more remarkable fossils to be discovered from this new site are fossil spiders. Whilst modern spiders are all too common in our homes, fossil spiders from the ancient past are extremely rare. This is because their exoskeletons are made of an organic material that typically breaks down quickly after death. However, fossils from the McGraths Flat site appear to have avoided such a destructive fate. This is likely due to iron-reducing bacteria effectively mummifying their bodies.

Before the Australian Museum’s discoveries at McGraths Flat, only four fossil spiders had been found across the entire continent. Now, from this single site alone we have managed to unearth 13 new spider specimens, most of which are completely preserved. These spiders aren’t all from the same species, either; they include members of the cobweb spider and trapdoor spider families. It’s highly likely they represent just one part of a complex ecological food web that existed in prehistoric Australia.

The work undertaken at McGraths Flat was funded by the descendants of Robert Etheridge Jr and the Australian Museum Foundation.

This article was originally printed in Explore, the Australian Museum Members' magazine. Read the issue.