Palaeontology is the study of ancient life from its fossil record in rocks and the genomic record of living organisms. The fossil record in South Australia spans more than 600 million years of Earth's history, from the origins of animals through to the rise and fall of Australian megafauna.
Current research by scientists and associates of the South Australian Museum focuses on four broad fields.
- The origins, evolution and early environments of animal life on Earth, based on fossils of Precambrian and Cambrian age spanning sites from Kangaroo Island, the Mount Lofty and Flinders Ranges. South Australia is famous for two groups of fossils that are helping to understand the origins of animal life on Earth.
- Fossils of the Ediacara Biota, first discovered and realised by the late Reg Sprigg AO in the Ediacara Hills and later discovered at many sites in the Flinders Ranges, north of Port Augusta and south of Marree. Ediacara fossils are unique as the oldest large and complex organisms on Earth, preserved as impressions in sandstone. They gave their name to the Ediacaran Period, the first new major time division to be defined in 120 years, and the first based on rocks in the Southern Hemisphere. The base of the Ediacaran is fixed as a point in rocks of the Flinders Ranges National Park, following a many decades of research on the fossils and rock formations of South Australia. Current research on Ediacara fossils is focused on excavating serial fossil seafloors in order to understand the ecology of these ancient marine communities.
Researchers: Jim Gehling, Mary Droser (University of California Riverside), Dennis Rice, and Mary-Anne Binnie.
- Fossils from the Early Cambrian Period, from many places in South Australia, represent the next chapter in the history of marine animals — often referred to as the “Cambrian explosion” of animals. Our research has focused on fossils of the Emu Bay Shale Biota that preserve minute details of early animals with and without mineral skeletons. These fossils preserve not only body outlines, but also gut contents, appendages and even eyes, in almost live quality. Together with tiny shells and other microfossils from Cambrian rocks of South Australia, the Emu Bay fossils document the rapid evolution of marine life following the extinction of most Ediacara fossil groups. Our research is helping to understand the palaeoecological changes that led to rapid evolution of animal groups which are present in modern marine ecosystems.
Researchers involved: Mike Lee, John Paterson (University of New England), Jim Jago (University of South Australia) Diego Garcia-Bellido, Jim Gehling, Greg Edgecombe (Natural History Museum, London) and Glen Brock (Macquarie University).
- The genetic differences between living animals can be used to infer relationships between groups, as well as estimate timing of evolutionary divergence, using “molecular clock” approaches. These predictions can be tested and refined using the fossil evidence. New Bayesian approaches (originally developed for molecular genetic analysis) can be applied to anatomical traits and the fossil record, to estimate broad evolutionary patterns. Current research focuses on several key problems, such as “how fast was evolution during the big bang of animal evolution — the Cambrian explosion”, and “did modern mammals diversify slowly while the dinosaurs were still alive, or did they evolve rapidly after the dinosaur extinctions?”
Researchers involved: Mike Lee, Robin Beck (University of NSW).
The younger rocks and soils of South Australia preserve a wide range of vertebrate and invertebrate fossils.
- The great inland seas that covered up to one half of Australia around 110 million years ago preserved evidence of marine life at the time of the dinosaurs. In the Cooper Pedy and Andamooka regions, fossils of marine reptiles, fish and invertebrates have been unearthed by opal miners and during targeted museum expeditions. These fossils include most of the world’s opal fossils, and provides our palaeontologists with the opportunity of reconstructing marine and terrestrial life in the Mesozoic Era, during the age of dinosaurs.
Researchers involved: Ben Kear (University of Uppsala) and Mike Lee.
- During the Cenozoic Era, when Australia broke free of Antarctica and drifted north, the southern coasts were flooded by the ocean. Shelly sandstone formations of the Murray, St Vincent and the Nullarbor basins abound with marine shelly fossils, and less commonly, the fossil bones of early whales. Non-marine sediments of the Lake Eyre Basin in the north of the state contain diverse vertebrate faunas of Tertiary age, including lungfish, crocodiles and strange marsupials. Current research by our palaeontologists and Flinders University is focusing on the diverse marsupial and reptilian vertebrate fossil faunas from the Nullarbor Plain and World Heritage Naracoorte Caves National Park and alluvial sediments around South Australia. These projects hope to find the reasons for extinction of much of our ancient megafauna.
Personnel Involved: Rod Wells (Flinders University), Gavin Prideaux (Flinders University), Trevor Worthy (Flinders University), Neville Pledge (Honorary Research Associate, South Australian Museum).