A REEXAMINATION OF THE DIVERSITY, TAXONOMIC DESCRIPTION AND PALEOECOLOGICAL RELATIONSHIPS OF SILURIAN CRINOIDS FROM WEST-CENTRAL AND SOUTHWEST OHIO

Recent studies focusing on lower to middle Silurian stratigraphy in active carbonate quarries of west-central and southwestern Ohio has resulted in the discovery of a moderately diverse crinoid fauna, including new taxa. The last comprehensive study of the mid-Silurian crinoid fauna of the Silurian carbonates in west-central and southwestern Ohio was included in the 1900 study by Stewart Weller, “The Paleontology of the Niagaran Limestone in the Chicago Area.” Since then, a limited number of individual studies have identified additional faunas found within the Silurian bedrock, particularly the Brassfield Formation and the Cedarville “Dolomites”.

In a detailed study of the Niagara formation of west-central Ohio, Daniel A. Busch (1942) identified 24 crinoid species from the Cedarville Dolomite. Further studies conducted by William Ausich reported that while there are more than 35 species identified from the lower Silurian Brassfield formation, only four Monobathrid camerate crinoids have been described from the Niagaran formation, comprised of the Dayton Formation, Osgood shale, Laurel limestone, Massie shale, Euphemia dolomite, Springfield dolomite, and Cedarville dolomite.

Current research in these bedrock deposits of Shelby, Miami, Mercer, and Dark counties, has uncovered a greater diversity of Silurian crinoids than originally documented – many of which have not been described nor identified. Unidentified genera and species found within rock formations can be important factors in understanding past and present environmental conditions, morphological variations and evolutionary traits. Categorizing any particular species is of paramount importance in understanding the evolutionary history and paleoecology of any group as a whole.

Determination of these organisms' identification will most certainly help fill in the gaps that remain in the historical existence of these marine organisms as well as the possibility in revealing new, unfounded species. A complete reexamination of this fauna will result in a detailed description, and if required, genus and or species classification of these newly discovered crinoids.