Abstract Ecological studies have revealed that the functional roles of dominant species in modern communities are often more important than overall diversity in governing community composition and functioning. Despite this recognition that abundance and diversity data are both required for a complete understanding of ecological processes, many paleoecological studies focus on presence-absence data, possibly because of concerns regarding the taphonomic fidelity of time-averaged fossil accumulations. However, the abundance of organisms in shell beds has been shown to provide a fairly accurate record of the living community, suggesting that the benefits of relative-abundance data should be reconsidered. Recognition of ecologically dominant species in local fossil assemblages should be based on counts of relative abundance and assessment of ecological role. Ecological dominance at larger spatial or temporal scales can be quantified using the mean rank order of a clade and the proportion of assemblages where t...
Research Article| March 20, 2019 INCREASE IN CARBONATE CONTRIBUTION FROM FRAMEWORK-BUILDING METAZOANS THROUGH EARLY CAMBRIAN REEFS OF THE WESTERN BASIN AND RANGE, USA DAVID R. CORDIE; DAVID R. CORDIE 1University of Wisconsin-Milwaukee, Department of Geosciences, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA Search for other works by this author on: GSW Google Scholar STEPHEN Q. DORNBOS; STEPHEN Q. DORNBOS 1University of Wisconsin-Milwaukee, Department of Geosciences, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA Search for other works by this author on: GSW Google Scholar PEDRO J. MARENCO PEDRO J. MARENCO 2Bryn Mawr College, Department of Geology, 101 North Merion Ave., Bryn Mawr, Pennsylvania, 19010, USA Search for other works by this author on: GSW Google Scholar Author and Article Information DAVID R. CORDIE 1University of Wisconsin-Milwaukee, Department of Geosciences, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA STEPHEN Q. DORNBOS 1University of Wisconsin-Milwaukee, Department of Geosciences, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA PEDRO J. MARENCO 2Bryn Mawr College, Department of Geology, 101 North Merion Ave., Bryn Mawr, Pennsylvania, 19010, USA email: drcordie@uwm.edu Publisher: SEPM Society for Sedimentary Geology First Online: 20 Mar 2019 Online Issn: 1938-5323 Print Issn: 0883-1351 Copyright Copyright #x000A9; 2019, SEPM (Society for Sedimentary Geology) PALAIOS (2019) 34 (3): 159–174. https://doi.org/10.2110/palo.2018.085 Article history First Online: 20 Mar 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation DAVID R. CORDIE, STEPHEN Q. DORNBOS, PEDRO J. MARENCO; INCREASE IN CARBONATE CONTRIBUTION FROM FRAMEWORK-BUILDING METAZOANS THROUGH EARLY CAMBRIAN REEFS OF THE WESTERN BASIN AND RANGE, USA. PALAIOS 2019;; 34 (3): 159–174. doi: https://doi.org/10.2110/palo.2018.085 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 SocietyPALAIOS Search Advanced Search ABSTRACT During the early Cambrian, organisms with robust skeletons began to integrate with microbialite reef structures. Specifically, archaeocyathan sponges were among the first metazoan reef-builders. Here we investigate the transition from microbial-dominated reef environments to metazoan-based reefs from strata in the western Basin and Range of California and Nevada. This study integrates point count data from petrographic thin sections with stable carbon isotopic and elemental composition of carbonates. From the earliest reef bearing formations to the latest, metazoan framework contribution increases from zero to 29.7%. This increase is linked to the addition of new framework-building organisms, namely coralomorphs, as well as an increase in archaeocyath body size. Correspondingly, Shannon's diversity increases from 0.652 to 1.492. However, skeletal contributions from additional organisms within the reefs (e.g., trilobites, echinoderms) appear unchanged and their diversity is not correlated with framework-builder diversity. A positive carbon isotopic excursion within the Lower Poleta Formation correlates with decreases in the abundances of uranium and molybdenum that suggest a global change in organic carbon burial as opposed to localized or diagenetic factors. This allows for chemostratigraphic correlation to published carbon isotopic data and provides a proposed regional age constraint of roughly 517 million years. Overall, early Cambrian reefs at this location exhibit a pattern of increasing metazoan contribution during the transition from microbial- to metazoan-based reef support, however, diversity remained low until additional organisms evolved to inhabit these ecosystems. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
