Homologous skeletal secretion in tommotiids and brachiopods

Abstract

Research Article| December 01, 2009 Homologous skeletal secretion in tommotiids and brachiopods Uwe Balthasar; Uwe Balthasar * 1Department of Earth Sciences, Uppsala University, Villavägen 16, 75236 Uppsala, Sweden †Current address: Department of Geographical and Earth Sciences, Glasgow University, Gregory Building, Lilybank Gardens, G12 8QQ Glasgow, UK *E-mails: uwe.balthasar@ges.gla.ac.uk; Christian.skovsted@geo.uu.se; lars.holmer@pal.uu.se; gbrock@els.mq.edu.au. Search for other works by this author on: GSW Google Scholar Christian B. Skovsted; Christian B. Skovsted * 1Department of Earth Sciences, Uppsala University, Villavägen 16, 75236 Uppsala, Sweden *E-mails: uwe.balthasar@ges.gla.ac.uk; Christian.skovsted@geo.uu.se; lars.holmer@pal.uu.se; gbrock@els.mq.edu.au. Search for other works by this author on: GSW Google Scholar Lars E. Holmer; Lars E. Holmer * 1Department of Earth Sciences, Uppsala University, Villavägen 16, 75236 Uppsala, Sweden *E-mails: uwe.balthasar@ges.gla.ac.uk; Christian.skovsted@geo.uu.se; lars.holmer@pal.uu.se; gbrock@els.mq.edu.au. Search for other works by this author on: GSW Google Scholar Glenn A. Brock Glenn A. Brock * 2Department of Biological Sciences, Macquarie University, NSW 2109, Australia *E-mails: uwe.balthasar@ges.gla.ac.uk; Christian.skovsted@geo.uu.se; lars.holmer@pal.uu.se; gbrock@els.mq.edu.au. Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (12): 1143–1146. https://doi.org/10.1130/G30323A.1 Article history received: 17 Apr 2009 rev-recd: 13 Jul 2009 accepted: 15 Jul 2009 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Uwe Balthasar, Christian B. Skovsted, Lars E. Holmer, Glenn A. Brock; Homologous skeletal secretion in tommotiids and brachiopods. Geology 2009;; 37 (12): 1143–1146. doi: https://doi.org/10.1130/G30323A.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 Tommotiids are distinctive components of the early Cambrian small shelly fauna, almost invariably represented by isolated phosphatic sclerites derived from a multielement protective cover (scleritome). The unusual range of tommotiid sclerite morphologies and unknown construction of the scleritome have severely hampered our understanding of their phylogenetic affinities. However, recent description of rare, articulated scleritome material belonging to the tommotiid genera Eccentrotheca and Paterimitra support the hypothesis that some tommotiids fall within the stem group of the lophophorate phyla Phoronida and Brachiopoda and that at least some tommotiid sclerites are homologous precursors of the shells of organophosphatic brachiopods. Here we show that the shell microstructure of Eccentrotheca and Paterimitra share substantial similarities with paterinid brachiopods. While paterinids possess an overall brachiopod morphology, their microstructure appears more similar to Eccentrotheca and Paterimitra than to nonpaterinate lingulids. These findings strongly support the existence of a brachiopod total group that is solidly rooted within tommotiids, and identify the organophosphatic skeletal composition as plesiomorphic with calcareous shells as derived. The microstructural changes of the proposed tommotiid-brachiopod transition probably reflect an adaptation to fluctuating food and phosphorous intake that came with the switch to a sessile life style at the base of the tommotiid clade. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.