LATE DEVONIAN CONODONTS AND FACIES FROM THE SHALLOW SHELF STRATA OF THE BROKEN RIB AND COFFEE POT MEMBERS, DYER FORMATION, CHAFFEE GROUP, CENTRAL COLORADO

The Dyer Formation in central Colorado consists of the conodont-rich Broken Rib Member comprised primarily of biopackstones, biowackestones, and mudstones and the overlying, generally poorly fossiliferous Coffee Pot Member which is characterized by dolomitized mudstones and intrarudstones as well as rare stromatolites, karsted intervals, sandstones, and bioclastic beds. The Broken Rib Member contains a diverse conodont fauna characterized by Bispathodus, Polygnathus, Pandorinellina, Icriodus, and Apatognathus indicative of the granulosus (Upper trachytera) Zone to expansa (Lower expansa) Zone based on the overlapping ranges of Polygnathus obliquicostatus and Icriodus costatus costatus that are typical of a tropical shelf setting. The Coffee Pot Member has yielded Pandorenellina cf. P. insita, Icriodus costatus darbyensis, and Polygnathus perplexus? indicative of the expansa Zone to ultimus Zone typical of a shallow shelf setting interbedded with facies indicative of even shallower water. At the Crane Park locality biowackestones rich in fish teeth and odd algal? mudstones suggestive of very shallow water did not yield any conodonts.