Early middle devonin conodont faunas (Eifelia, costatus-kockelianus zones) foom the Roberts Mountains and adjacent areas in Central Nevada

Abstract

Conodont faunas from the uppermost part of the Coils Creek Member of the McColley Canyon Formation and primarily the lower part of the Denay Limestone (Middle Devonian, Eifelian) from the northern Roberts Mountains and adjacent central Nevada areas are the subjects of the present study. Four new species from the Denay Limestone (Eifelian, costatus and australis zones) are described herein: Polygnathus salixensis sp. nov., P. holynensis sp. nov., P. robertsensis sp. nov. and P. damelei sp. nov. These species add to the biostratigraphic resolution and characterization of the costatus and australis zones. The basal Denay Limestone in the northern Roberts Mountains is in the upper part of the costatus Zone, which directly overlies the upper Coils Creek Member in the serotinus Zone. Thus, the patulus and partitus zones are missing in this area. To the south in the northern Antelope Range and the northern Hot Creek Range, the partitus Zone sits directly on the serotinus Zone with the patulus Zone missing.