The Emu Bay Shale Revisited: New Discoveries from a Lower Cambrian Lagerstätte in South Australia
John R. Paterson1†, Gregory D. Edgecombe2, Diego C. García-Bellido3, James G. Gehling4, James B. Jago5, Michael S. Y. Lee4,6
1 Division of Earth Sciences, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
2 Department of Palaeontology, Natural History Museum, London, UK
3 Departamento de Paleontología, Instituto de Geología Económica (CSIC-UCM), Madrid, Spain
4 South Australian Museum, North Terrace, Adelaide, Australia
5 School of Natural and Built Environments, University of South Australia, Mawson Lakes, Australia
6 School of Earth and Environmental Sciences, University of Adelaide, Australia
The Lower Cambrian (Series 2) Emu Bay Shale lagerstätte on the north-east coast of Kangaroo Island, South Australia, first discovered in the 1950s, remains Australia’s most informative Burgess Shale-type locality. Previous research on the Emu Bay Shale agerstätte has focused on collections sourced from the cliff and wave-cut platform exposures outcropping on the shoreline immediately east of the mouth of Big Gully, approximately 3 km east of Emu Bay. Recent excavations at a new locality situated further inland (Buck Quarry) have revealed a far greater diversity of organisms than previously recognized from the lagerstätte, including taxa known from other Cambrian lagerstätten. Better-preserved soft-bodied structures of several previously-known taxa were also recovered.
The Buck Quarry biota is dominated by arthropods in terms of abundance and diversity. Trilobites are the most common fossils, particularly Estaingia bilobata and Redlichia takooensis; antennae and thoracic appendages are sometimes preserved in R. takooensis. The most abundant non-mineralized arthropods are bivalved taxa, including Isoxys communis and Tuzoia australis, alongside new species of these genera; specimens of these taxa commonly preserve eyes, cephalic and trunk appendages, and midgut glands. Putative stem-group arthropods are relatively rare at Buck Quarry. Representative specimens include frontal appendages and lateral flaps of Anomalocaris, as well as the enigmatic Myoscolex ateles; the rare occurrence of the latter at Buck Quarry contrasts with it being the most common non-mineralized taxon from the shoreline outcrop. Other new arthropod taxa include a possible xandarellid, a megacheiran with affinities to genera such as Alalcomenaeus, Leanchoilia and Utahcaris, in addition to a new family within the Nektaspida (including two new monotypic genera) that represents a sister group to Naraoiidae + Liwiidae.
The other members of the biota represented at Buck Quarry comprise leptomitid demosponges; palaeoscolecids (including Palaeoscolex antiquus); hyoliths; chancelloriids; linguliformean brachiopods; a banffozoan; an Odontogriphus-like taxon; and a variety of other problematic forms.
Oral presentation | Wed Aug 5th, 08:40