Conodont biostratigraphy and paleoecology of Middle Ordovician rocks in eastern Oklahoma

Abstract

Conodonts from the upper Burgen, Tyner, and Fite Formations (Middle Ordovician) of eastern Oklahoma include two new species,Phragmodus harrisiandPlectodina tynerensis. The conodont fauna indicates that the upper Burgen through middle Tyner is Whiterockian (pre- to earliest Chazyan) and that the upper Tyner–Fite is probably Kirkfieldian in age.The Whiterockian Burgen–Tyner preserves a regressive succession of shoreface, lagoonal, and intertidal deposits. That change is reflected by the conodont succession, which shows replacement of a fauna dominated by species ofNeomultioistodus, Scandodus?, andParaprioniodusby one dominated by species ofPhragmodus, Plectodina, andErismodus.Carbonate deposits of the Kirkfieldian(?) upper Tyner and Fite Formations follow a major hiatus and reflect shallow, subtidal to intertidal conditions. The conodont fauna is composed of species ofAphelognathus, Plectodina, Curtognathus, Erismodus, andOulodus, among others.