CALL FOR PROPOSALS:

ORGANIZERS

  • Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC

 

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Paper No. 8
Presentation Time: 3:30 PM

PHYLOGENETIC REVISION OF THE ORDOVICIAN BRACHIOPOD GENUS GLYPTORTHIS


WRIGHT, David F., School of Earth Sciences, Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210 and STIGALL, Alycia L., Department of Geological Sciences and Ohio Center for Ecology and Evolutionary Studies, Ohio University, 316 Clippinger Lab, Athens, OH 45701, wright.1433@osu.edu

The genus Glyptorthis, Foerste 1914, comprises a diverse, cosmopolitan clade of orthid brachiopods characterized by the presence of strongly lamellose concentric ornamentation patterns on the exterior of their shells. Glyptorthids are common constituents of Middle Ordovician to Lower Silurian benthic marine faunas of North America. A phylogenetically informed revision of Glyptorthis is presented here as part of a larger project which aims to assess phylogenetic biogeographic patterns among Ordovician orthides. Glyptorthis insculpta (Hall 1847) participated in the Upper Ordovician Richmondian Invasion into the Cincinnati region. A species-level phylogenetic analysis of Glyptorthis may, therefore, yield insight for testing hypotheses regarding the evolutionary and biogeographic origin of the Richmondian invaders.

Type specimens from museum collections were examined to determine character states for phylogenetic analysis of all North American species of Glyptorthis. Non-type and specimens figured in the literature were also examined when possible to assess the range of morphologic variation within each species. A phylogenetic analysis was performed on both internal and external morphological characters using parsimony-based PAUP software and analyzed with MacClade. Both discrete and continuous characters were used. Continuous characters states were differentiated through morphometric analysis and coded as qualitative states.

A set of well supported trees were recovered from parsimony analysis. The strict consensus of these is highly resolved and delineates four monophyletic clades within the genus. Each clade is supported by multiple synapomorphies. These relate primarily to characters of shell ornamentation, valve convexity, shape of the ventral muscle field, and angular relationships within the ventral cardinal area. Preliminary biogeographic analysis suggests that G. insculpta invaded the Cincinnati region from basins in either the central or southeast USA.

Session No. 131

T52. Species and Speciation in the Fossil Record II
Monday, 10 October 2011: 1:30 PM-5:30 PM
Room 205CD (Minneapolis Convention Center)
Geological Society of America Abstracts with Programs. Vol. 43, No. 5, p.333
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