WELL PRESERVED CONODONT APPARATAL ELEMENTS FROM THE PENNSYLVANIAN AND PERMIAN, USA

Two localities that have yielded well preserved conodonts from the Middle Pennsylvanian and the Middle Permian show the intricacy of Pennsylvanian apparatal elements and the probable apparatus of a Middle Permian coniform apparatus with no recognized immediate predecessor for millions of years.

A moderately well preserved conodont fauna was recovered from a limestone concretion from the Excello Shale Member of the Mouse Creek Formation of the Marmaton Group (upper Moscovian, Pennsylvanian) of Iowa. Complete sets of apparatal elements for Gondolella, Idiognathodus, Idioprioniodus, and Neognathodus are represented. The elements of Idiognathodus and Neognathodus are very similar. Idioprioniodus and Gondolella, though having similar elemental plans, are distinct and Idioprioniodus elements attain a much larger size than similar elements of Gondolella.

Abundant specimens of the coniform conodont Caenodontus were recovered from several beds in a section of the Hegler Limestone Member of the Bell Canyon Formation (Wordian, Middle Permian) in West Texas. The section represents a basinal depositional setting and the coniform bearing beds represent initial deposition of the Hegler Limestone. The coniform elements display a variety of morphologies and can be placed into an apparatal display similar to those from the Lower Ordovician.