Conodonts from a platform-to-basin transect, lower Ordovician to lower Silurian, northeastern British Columbia, Canada

Abstract

The conodont fauna from nine sections across a platform-to-basin transect in northeastern British Columbia includes species of Early Ordovician (Tremadocian) to Early Silurian (Llandovery) age. A collection of 9,110 conodont elements was recovered from 205 samples taken from nine stratigraphic sections that preserve the platform succession of the Kechika, Skoki, Beaverfoot, McCusker and Nonda Formations and their off-shelf equivalents, the Ospika, Robb, Kenny and Laurier Formations of the Road River Group. The fauna is assigned to 106 species representing 67 genera; the Ordovician species are representative of two faunal realms. One new genus, left in open nomenclature, is described. Five new species includeDrepanoistodus latusand four new species left in open nomenclature assigned to the following genera:Walliserodus, Multioistodus?,Pseudooneotodus, andBelodina. The Midcontinent Realm zones recognized include, in ascending order, theAcodus kechikaensis, Oepikodus communis, Jumudontus gananda, Tripodus laevistoPlectodina aculeatazones,Phragmodus undatusandGamachignathus ensifer? zones. Zonal species of the Atlantic Realm areMicrozarkodina flabellum, Eoplacognathus suecicus, Baltoniodus variabilis, Pygodus anserinus, andAmorphognathus tvaerensis. The Silurian fauna, of lower diversity than the Ordovician fauna, is representative of theDistomodus staurognathoidesandPterospathodus amorphognathoideszones.