NORTH AMERICAN REFERENCE SECTIONS FOR OSAGEAN CONODONT ZONATION

Two excellent distal shelf Osagean stratigraphic sections containing a continuous succession of conodonts of upper Kinderhookian-upper Osagean age from the Ozark Region in southwestern Missouri is presented. The first locality is the Roaring River State Park road-cut section on Missouri State Highway 112 first published by Branson and Mehl (1941). This section of some 40 meters comprises the Bachelor Formation, Compton Formation, Northview Formation, Pierson Formation, and the Reed Springs Formation. This section is the type locality for the type species of the following significant genera Scaliognathus, Doliognathus, and Bactrognathus. This locality is the type section for a number of Osagean conodont zonal name bearers including Scaliognathus anchoralis Branson and Mehl, Doliognathus latus Branson and Mehl , Gnathodus bulbosus Thompson and Polygnathus mehli Thompson. The Osagean part of the the Roaring River locality contains the communis carina Zone, multistriatus Zone, anchoralis-latus Zone, distortus Zone, mehli Zone, and the bulbosus zone.

A second exposure in southwestern Missouri is the magnificent new road-cut on US 71 at Jane, Missouri. This fifty meter section comprises the “Chattanooga” Shale, Bachelor Formation, Compton Formation, Northview Formation, Pierson Formation, and the Reed Springs Formation. In addition to the above zones, the texanus Zone is also present near the top of the Pierson Formation, thus yielding all Osagean conodont zones in one locality without any significant missing section.

These two sections taken collectively represent excellent North American reference sections in non-condensed open marine environments without any significant missing section. New undescribed taxa are also presented herein awaiting formal description.