The picturesque Flinders Ranges in South Australia holds a fascinating story of long-past lives underground. To uncover these secrets an outstanding research team led by Environment Institute’s A/Prof. Diego Garcia-Bellido (UofA/SA Museum), Dr. Jim Gehling (South Australian Museum), Prof. Mary Droser (Univ. of California-Riverside ) and Prof. Bob Gaines (Pomona College, California), were awarded an Australian Research Council (ARC) 2022 Discovery Project.
The Ediacaran is the geological period when the first complex, multicellular life appeared in our planet, known as the Ediacara Biota, more than half a billion years ago. Although fossils of these early organisms are found worldwide e.g. Canada, China, Russia, Namibia, the best record of this biota is in the Flinders Ranges, South Australia.
A new distinct rock unit has been identified and named Nilpena Member. The Nilpena Member overlays the famous, very fossiliferous, Ediacara Member (named after the Ediacara Hills, where these fossils were first found). This project aims to describe the rocks and fossils of this new member, as well as its extension throughout the Flinders Ranges. The team is excited by several new species already found that were previously unknown to science.
One of the most important components of this ARC-funded Discovery project was drilling through the fossiliferous beds of the Nilpena and Ediacara members, down to the top of the unfossiliferous Chace Member. Two 6 cm-wide cores were drilled down to 65 and 75 meters, in two localities 2.5 km apart at Nilpena Ediacara National Park. You can see below the video of the whole drilling process, produced by this University of Adelaide and SA Museum partnership.
Both cores have now been brought back to Adelaide, where petrographical and geochemical analyses will be carried out in the next two years. Among our biggest questions is dating the Ediacaran fossils in Australia, so far this has only been an estimation based on Russian material, which is 555 million years old. We will search for ash layers in the core samples to obtain zircons to enable accurate dating of the Australian Ediacara Biota. These zircon crystals would also help us determine the presence and extent of a sedimentary gap at the Ediacara/Nilpena member boundary.
If the dates in each rock member are different, this could indicate that the change in fossil species through time in the same location would constitute the oldest continuous ‘faunal succession’ in the fossil record. Furthermore, this could allow us to determine if the rate of evolution observed in Australia’s Ediacaran assemblages differs from that observed in the Phanerozoic, when animals became widespread, and predation became a major driver of evolution.
The results of this ARC Project will strengthen the Flinders Ranges UNESCO World Heritage nomination led by the Department of Environment and Water. This nomination also includes Ikara-Flinders Ranges National Park, Vulkathunha-Gammon Ranges National Park, and Arkaroola Protection Area.