A new chancelloriid from the Emu Bay Shale (Cambrian Stage 4) of South Australia

Abstract

<I>Chancelloria australilonga</I> sp. nov. is described from the Emu Bay Shale (Cambrian Series 2, Stage 4) of Kangaroo Island, South Australia. The new species has a typical sac-like body, equipped with a meshwork of dozens of distinctive rosette-like sclerites. Each sclerite comprises one central ray and six or seven lateral rays, and is characterized by a pair of remarkably long and subparallel adapical rays. <I>Chancelloria australilonga</I> is one of the few chancelloriid species preserved with an apical orifice with an obvious peripheral tuft. The tuft consists of a series of single-rayed sclerites with inflated bases. The preservation of the specimens, coupled with sedimentological information and their general rarity in the Emu Bay Shale, suggests short-distance transport and subsequent deposition in a nearshore, low-oxygen preservational trap. Additionally, the known distribution of chancelloriids in the well-documented Konservat-Lagerstätten representing a variety of sedimentary environments, indicates that chancelloriids, especially the genus <I>Chancelloria</I>, were likely adapted to an extensive range of habitats.