The scleritome of Eccentrotheca from the Lower Cambrian of South Australia: Lophophorate affinities and implications for tommotiid phylogeny

Abstract

Research Article| February 01, 2008 The scleritome of Eccentrotheca from the Lower Cambrian of South Australia: Lophophorate affinities and implications for tommotiid phylogeny Christian B. Skovsted; Christian B. Skovsted 1Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden Search for other works by this author on: GSW Google Scholar Glenn A. Brock; Glenn A. Brock 2Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia Search for other works by this author on: GSW Google Scholar John R. Paterson; John R. Paterson 3Division of Earth Sciences, School of Environmental and Rural Science, University of New England, Armidale NSW 2351, Australia Search for other works by this author on: GSW Google Scholar Lars E. Holmer; Lars E. Holmer 4Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden Search for other works by this author on: GSW Google Scholar Graham E. Budd Graham E. Budd 4Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden Search for other works by this author on: GSW Google Scholar Geology (2008) 36 (2): 171–174. https://doi.org/10.1130/G24385A.1 Article history received: 24 Aug 2007 rev-recd: 15 Oct 2007 accepted: 15 Oct 2007 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Christian B. Skovsted, Glenn A. Brock, John R. Paterson, Lars E. Holmer, Graham E. Budd; The scleritome of Eccentrotheca from the Lower Cambrian of South Australia: Lophophorate affinities and implications for tommotiid phylogeny. Geology 2008;; 36 (2): 171–174. doi: https://doi.org/10.1130/G24385A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The first partially articulated scleritome of a tommotiid, Eccentrotheca sp., is described from the Lower Cambrian of South Australia. The Eccentrotheca scleritome consists of individual sclerites fused in a spiral arrangement, forming a tapering tube-shaped skeleton with an inclined apical aperture and a circular to subcircular cross section. Traditionally, tommotiid sclerites have been assumed to form a dorsal armor of imbricating phosphatic plates in slug-like bilaterians, analogous to the calcareous sclerites of halkieriids. The structure of the Eccentrotheca scleritome is here reinterpreted as a tube composed of independent, irregularly shaped sclerites growing by basal-marginal accretion that were successively fused to form a rigid, protective tubular structure. The asymmetrical shape and sometimes acute inclination of the apical aperture suggests that the apical part of the scleritome was cemented to a hard surface via a basal disc, from which it projected vertically. Rather than being a vagrant member of the benthos, Eccentrotheca most likely represented a sessile, vermiform filter feeder. The new data suggest that the affinities of Eccentrotheca, and possibly some other problematic tommotiids, lie with the lophophorates (i.e., the phoronids and brachiopods), a clade that also possesses a phosphatic shell chemistry and a sessile life habit. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.