Conodonts and Biostratigraphy of the Permian

Sequences of Permian samples from the western United States include specimens of most species described from single samples from Greenland, Germany, Sicily, Greece, Pakistan, and China. Wolf-campian collections from Nevada and Utah include abundant Idio-gnathodus,some Adetognathusand “Gnathodus,”and representatives of a few Gondolellaspecies. Two assemblage zones are recognized in the Nevada Riepe Springs and Riepetown Formations (Wolfcampian) ; the Idiognathodus ellisoniAssemblage Zone in the lower part and the Gondolella bisselli-Spathognathodus whiteiAssemblage Zone in the upper part. Elements of the faunas of these zones have been reported from the Kansas Big Blue Group and the Wyoming Tensleep Formation. Leonardian faunas are poorly known but lower Leonard strata include sequences of samples with Streptognathodus sulcoplicatus,and younger Leonardian rocks contain specimens of this species and representatives of Gondolella,including G. idahoensis.Early Guada-lupian (Wordian) strata contain the Gondolella serratafauna, which includes many of the same species that are present in older Leonardian rocks, and a fauna characterized by Neospathodus arcucristatus.Higher Guadalupian (probably lower Capitanian) rocks are characterized by abundant Gondolella rosenkrantzi.The Plympton and Gerster Formations of eastern Nevada contain the N. arcucristatusand G. rosenkrantzifaunas, respectively, and upper Gerster beds contain Neospathodus divergens.Elements of these faunas have also been reported from late Guadalupian or younger strata in the German Zechstein and in Greenland. Youngest Permian conodonts known are those described by Sweet (1970) from Pakistan and include species formerly assigned to Spathognathodus. Earliest Permian faunas are dominated by platform genera of Late Pennsylvanian type. These rapidly became extinct during the later Early Permian and were replaced during the Middle and Late Permian by new species of Gondolella, Neospathodus,and several new genera, some of which are also important in Early Triassic faunas.