Edrioasteroids-KPS Talk

[Dan Phelps <JFCOST00@UKCC.uky.edu>]

A dinosaur list member requested that I post a summary of Dr. David
Meyer's talk to the November meeting of the Kentucky Paleontological
Society.  Dr. Meyer kindly gave me permission to post the abstract
of his paper- "Population Paleoecology and Comparative Taphonomy of
Two Edrioasteroid (Echinodermata) Pavements: Upper Ordovician of
Kentucky and Ohio" which appeared in the journal ^Historical Biology^
Vol. 4, pp. 155 - 178 (1990).
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POPULATION PALEOECOLOGY AND COMPARITIVE TAPHONOMY OF TWO EDRIOASTEROID
(ECHINODERMATA) PAVEMENTS: UPPER ORDOVICIAN OF KENTUCKY AND OHIO
                         BY: David L. Meyer
                        University of Cincinnati

Key words: edrioasteroid, echinoderm, epizoans, Ordovician, paleoecology,
           taphonomy.

ABSTRACT

Two strophomenid brachiopod shell pavements bearing abundant edrioasteroid
epizoans occur stratigraphically within the top 4.5 m of the Corryville
Formation (Upper Ordovician, Maysvillian) in Boone County, Kentucky, and
Hamilton County, Ohio.  Both assemblages are dominated by ^Isorophus
cincinnatiensis^ and contain ^Carneyella pilea^ and ^Streptaster
vorticellatus^ as lesser constituents.  Pedicle exterior valves of
^Rafinesquina "alternata"^ are the perferred substratum for all
species at both sites, but the Kentucky population occurs mainly on
unabraded, articulated shells and the Ohio population occupies
abraded, disarticulated shells.  The Kentucky population includes a
greater size range of ^Isorophus^ (at least three cohorts) than the
Ohio population (at least two cohorts), suggesting a greater time span
of colonization for the Kentucky site.  Host shells from Kentucky have
anterior-posterior axes strongly aligned NE-SW wheras the Ohio shells
are unoriented.  ^Isorophus^ in Kentucky show a preference for the
anterior margin of the ^Rafinesquina^ pedicle exterior valve, whereas
^Isorophus^ in Ohio show no prefered location on host shells.  The
Kentucky edrioasteroids are inferred to have attached to mainly live
^Rafinesquina^ in brachial-valve-up position.  Host shells were inverted
and oriented by a NE-SW storm surge, then buried rapidly.  Ohio
edrioasteroids occupied mainly dead, already inverted host shells not
oriented by storm surge possibly because of their more downslope (distal)
location.  Comparative taphonomic relationships between the coeval
populations are consistant with a model of proximal to distal distribution
along a gentle shallow subtidal N-S paleoslope subject to episodic storm
activity.
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Dan Phelps         jfcost00@ukcc.uky.edu
(606) 277-3148     Ask me how to join
                   The Kentucky Paleontological Society!