CONODONTS FROM THE BROMIDE FORMATION (MIDDLE ORDOVICIAN), SOUTH-CENTRAL OKLAHOMA

Forty-seven samples of the Bromide Formation (Simpson Group) of south-central Oklahoma produced a collection of 10,216 conodonts assigned to 46 species. The conodont fauna is dominated by species of Phragmodus and Plectodina and indicates a latest Whiterockian to early Mohawkian (Black Riveran) or late Llandeilian to early Caradocian age. Five new species are named including Ansella crassa, Bryantodina aequalis, Plectodina edentula, Walliserodus declivis, and Pharagmodus ambiguus. The latter species is distinct from Phragmodus flexuosus Moskalenko, a species to which it has been assigned in past reports. Analysis of conodont distribution with respect to the shallow-water Bromide lithofacies distinguishes shallow to deeper water conodont associations. Samples from shallower water facies contain Ansella crassa n. sp., Cahabagnathus sweeti (Bergstrom), Curtognathus spp., Eoplacognathus elongatus (Bergstrom), Erismodus typus Branson and Mehl, Oneotodus? ovatus (Stauffer), Phragmodus ambiguus n. sp., Phragmodus flexuosus, and Staufferella falcata (Stauffer). Samples from deeper water facies contain forms such as Ansella nevadensis (Ethington and Schumacher) and Baltoniodus gerdae (Bergstrom).