The exceptional preservation of Aix-en-Provence spider fossils could have been facilitated by diatoms

Abstract

AbstractMuch of our understanding of the history of life on Earth comes from fossil sites with exceptional preservation. Here, we use microscopy and chemical analysis of spiders found in the Oligocene Aix-en-Provence Formation, France, to unravel the taphonomic pathway responsible for the preservation of these arachnids. Microscopy revealed the presence of diatom mats and a black polymer on the body of the spiders, while elemental analysis revealed the polymer was composed of co-localized carbon and sulfur. We hypothesize that the extracellular polymeric substances produced by the diatoms found widely in this deposit could have helped promote the sulfurization of the spiders. Additionally, examination of similar Fossil-Lagerstätten reveals that this preservation pathway may be widespread across the Cenozoic and, if so, would be responsible for much of our understanding of insect, arachnid, amphibian, and plant life preserved in lacustrine settings.