Taphonomy and palaeoecology of the emuellid trilobite Balcoracania dailyi (early Cambrian, South Australia)

摘要: Monospecific assemblages of the trilobite Balcoracania dailyi occur in lower Cambrian strata within Adelaide Geosyncline South Australia. Biostratinomic data from single bedding plane Warragee and Coads Hill Members Billy Creek Formation White Point Conglomerate reveal a range taphonomic signatures census to within-habitat, timeaveraged assemblages. These are interpreted as having inhabited protected, shallow, marginal marine environments. Size–frequency distributions, coupled with data, show that Member assemblage represents living population physically stressful environment tidally-influenced lagoon, while original structure has been lost due varying degrees overprinting. Integration taphonomic, stratigraphic sedimentological supports interpretation B. representing an opportunistic species. A preserved body cluster is considered characterise congregation formed for purpose synchronous reproduction ecdysis, one oldest examples gregarious behaviour arthropod fossil record. Furthermore, by analogy modern horseshoe crabs, high number juveniles (i.e., protaspides early meraspides) same believed be constituents nursery intertidal zone, adults migrating into shallows copulate spawn. Preserved moult ensembles have enabled description exuviation techniques dailyi. © 2007 Elsevier B.V. All rights reserved.