Untangling the taphonomy of the Early Cambrian Emu Bay Shale Konservat-Lagerstaette, South Australia

Martin Glaessner is best known for his work on the Ediacara biota of South Australia, but he also played a key role in documenting the early Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstaette on Kangaroo Island. Glaessner was the first to describe some of the more common soft-bodied species, including the arthropods Isoxys communis and Tuzoia australis, the priapulid Palaeoscolex antiquus, and the problematic taxa Myoscolex and Vetustovermis. Recent excavations by us at Buck Quarry have revealed a surprising diversity, with over 50 species now known. The EBS biota is dominated by euarthropods (>50%), with the remaining species diversity comprising various other ecdysozoans (e.g., priapulids and a lobopodian), sponges, molluscs, brachiopods, a polychaete annelid, and a variety of problematic forms. Although the constituent taxa represent a typical Burgess-Shale-type (BST) fauna, EBS fossils display a range of taphonomic modes that are otherwise rare in most other BST deposits. For example, recently documented arthropod eyes, including those of Anomalocaris, show two distinct modes, preserved as iron oxide (after pyrite) and calcium phosphate, demonstrating that disparate styles of early diagenetic mineralization can replicate the same type of extracellulartissue within a single BST deposit. This contrasts with many other BST deposits wherein recalcitrant tissues such as cuticle typically preserve as featureless carbon films. This demonstrates that the prevalence of early diagenetic mineralization of soft tissues seen in EBS fossils can provide much better anatomical resolution in some instances than other deposits around the world.