You mat have read recently about chemical fossils discovered in sedimentary rocks in Oman.   Those fossil steroids, remnants of a type of sponge known as Demosponges, are between 635 and 750 million years old. They date back to around the time of the Marinoan glaciation, the last of the huge ice ages at the end of the Neoproterozoic era.

The research suggests that the shallow waters in some late Cryogenian ocean basins contained dissolved oxygen in concentrations sufficient to support simple multicellular animals at least 100 million years before the rapid diversification of bilaterians — early animals with a bilateral symmetry — during an interval known as the Cambrian explosion by palaeontologists.

The dating was made possible using a scientific technique known as Hydropyrolysis - using hydrogen gas at high pressure.  

Colin Snape, Professor of Chemical Technology and Chemical Engineering, in the School of Chemical and Environmental Engineering, said: “This landmark study on marine ecosystems was made possible by the unique capability of hydropyrolysis to release key biomarkers from ancient rocks with minimal structural alteration.”

Hydropyrolysis — also known as HyPy — was developed into a commercial system through collaboration with Engineering&Quality Systems and reactor engineering specialist Strata Technology. It was originally designed to liquefy large quantities of coal and strip down complex mixtures of organic chemicals down to their pure carbon skeletons. The technology, which recently won The 2008 Engineer Business Support and Universities Award, also has applications for detecting steroid abuse and cleaning up charcoal samples for radiocarbon dating.

Using biomarker analysis, the discovery, by an international research team from America, Australia and the UK, represents the oldest evidence for animals in the fossil record, and the first evidence for animals predating the termination of the Marinoan glaciations, the second of the two major glacial episodes of the Neoproterozoic which terminated 635 million years ago.  

Dr Gordon Love, from the Department of Earth Sciences at the University of California, the principal author on the study said: “By establishing a robust stratigraphic and temporal framework for the Neoproterozoic-Cambrian South Oman Salt Basin strata and by employing state-of-the-art analytical techniques for biomarker recovery and analysis then we have unearthed the first fossil evidence for Cryogenian animals from the detection of anomalously high amount of distinctive steroids produced by sponges. We believe that we are converging on the correct date for the divergence of complex multicellular animal life, between 635 and 750 million years ago. It appears that the climatic shock of the two major glacial episodes of the Neoproterozoic caused a major reorganisation of marine ecosystems including the evolution of animal feeders living on the seafloor. In future, we and others will be screening other sedimentary rocks for animal steroids around and before the first glaciation event, the Sturtian, but so far no convincing signals have been detected prior to the Sturtian glaciation.”