"The biostratigraphy, paleoecology and paleontology of the Lower Ordovician Gasconade Formation in Missouri is reinvestigated in an attempt to solve problems that have arisen since the classic earlier studies by Ulrich, Bridge and others. Twelve faunal zones are established, many based on primitive mollusks which dominate the formation. The oldest of these, in the Van Buren Member, is the Hypseloaonus Zone. This is followed by a zone characterized by the primitive cephalopod Dakeoaeras then a zone dominated by the gastropod Sinuopea. These zones are succeeded by the Euomphalopsis, Matthevia and Ozarkina Zones which lie stratigraphically below the Cryptozoon Zone, a well known marker. Above the Cryptozoon Zone are the Helicotoma, Ophileta and Paahendoaeras Zones and the upper two zones are characterized by trilobite species, the Hystriaurus missouriensis and Hystriaurus brevispiaatus Zones. On the basis of this broad spectrum of fossils the Cambro-Ordovician boundary in the Ozarks remains between the Eminence and Gasconade formations. However, the Cambrian affinities of many Gasconade fossils such as Hypseloaonus and Matthevia are noted.
General broad lithologic variations of the Gasconade Formation and their paleoenvironments are considered through discussions of several major outcrop areas. A model for the paleoenvironment of the Gasconade proposes a shallow sea setting. Local concentrations of fossils are considered to represent areas where the water was deeper, possibly as a result of submarine karst topography.
New and diverse forms developed during this time and new elements in the Gasconade are described. These include one new hypseloconid monoplacophoran genus, Gasaonadeoaonus, and the species G. ponderosa, G. waynesvillensis and G. expansus. Two new species of the monoplacophoran Proplina are described: P. merameaensis and P. sibeliusi, and one new species of Shelbyoaeras, S. bigpineyensis. Three new species of the genus Matthevia (molluscan Class Mattheva) are described: Matthevia leviaosta, M. quinquelites and M. robustus, as well as one new species of the trilobite Hystriaurus, H. brevispiaatus "--Abstract, pages ii-iii.
Spreng, Alfred C., 1923-2012
Gale, Nord L.
Hagni, Richard D.
Stitt, James H.
Geosciences and Geological and Petroleum Engineering
Ph. D. in Geology
University of Missouri--Rolla
x, 183 pages
© 1978 Bruce Leonard Stinchcomb, All rights reserved.
Dissertation - Open Access
Geology, Stratigraphic -- Ordovician
Geology -- Missouri
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Stinchcomb, Bruce L., "The paleontology and biostratigraphy of the lower ordovician Gasconade formation of Missouri" (1978). Doctoral Dissertations. 330.