Eccentrotheca from the Lower Cambrian of South Australia – the first known tommotiid scleritome and its biological implications
2007 (English)In: 51st Palaeontological Association Annual Meeting: Programme with Abstracts, 2007, 55- p.Conference paper (Other scientific)
The discovery of the first partially articulated scleritome of a tommotiid, Eccentrotheca sp. from the Lower Cambrian of the Flinders Ranges in South Australia necessitates a complete revision of the gross morphology and biological function of the problematic tommotiids. The scleritome of Eccentrotheca is an expanding tubular structure with a circular cross-section that was formed by the episodic merging of individual cone-shaped sclerites. The basal region of the tube has an open aperture, the morphology and inclination of which varies considerably. Growth patterns in the apical region indicate that the aperture housed structures that helped anchor the tube to a hard substrate. The Eccentrotheca animal is consequently reinterpreted as a sessile, epibiotic filter-feeder. This model contrasts sharply to all previously published models of tommotiid animals, which almost without exception envisages a slug-like animal with a dorsal cover of imbricating sclerites (modelled after the scleritome of the coeval halkieriid animal). Tommotiids have been suggested to fall within the stem group of the Brachiopoda, mainly based on the organophosphatic composition and brachiopod-like shell structure of some tommotiids. The sessile, filter-feeding lifestyle inferred from the scleritome of Eccentrotheca appears to strengthen the lophophorate hypothesis of tommotiid relationships, although the tubicous habit of the scleritome is more reminiscent of phoronids than brachiopods.
Place, publisher, year, edition, pages
2007. 55- p.
IdentifiersURN: urn:nbn:se:uu:diva-12600OAI: oai:DiVA.org:uu-12600DiVA: diva2:40369