Revision of Lower Devonian (Emsian) brachiopod biostratigraphy and biogeography, central Nevada

Abstract

A diverse, previously unknown fauna with Skenidioides and other small brachiopods, ostracodes, trilobites, and corals has been dated as gronbergi Zone on coexisting conodonts. Conodonts date the Leptocoelina globosa fauna as serotinus Zone. Cymostrophia seca, Strophodonta luxor, and Atrypa kobar are new species. These assignments and new occurrences allow retabulation of most Emsian brachiopod ranges in Nevada.Plotting of provincial, endemic, and cosmopolitan brachiopod genera on a time vs. percent graph shows that the shift through time of Nevada faunas from Eastern Americas Realm to Old World Realm took place gradually during Emsian transgression. Endemic genera were prominent during early phases of Devonian transgression.