Leanne J. Pyle

Taxonomy, Evolution, and Biostratigraphy of Conodonts from the Kechika Formation, Skoki Formation, and Road River Group (Upper Cambrian to Lower Silurian), Northeastern British Columbia

Conodonts, the tiny, phosphatic, toothlike remains of an extinct group of early vertebrates, are the most important fossil group for biostratigraphy throughout their stratigraphic range from Late Cambrian to Late Triassic. The monograph presents the results of a significant project in remote regions of northeastern British Columbia. It extends the knowledge of the stratigraphic framework and conodont faunas into a region where information of this kind is largely unknown. Complete stratigraphic sections exposed in the high alpine of the Northern Rocky Mountains allowed examination of strata across a platform-shelfbreak-basin transect. The conodont faunas from the Kechika Formation, Skoki Formation, and Road River Group are described from an extensive collection of nine stratigraphic sections (over 9000 m measured) that yielded abundant conodont elements (38 600 total). This monograph represents a benchmark study of these important zonal fossils. The detailed paleontological work not only provides a taxonomic basis for future studies on early Paleozoic conodonts but also focuses on the evolution of conodonts in the early Ordovician, a time of extraordinary adaptive radiation. The taxonomic work provides detailed descriptions and illustrations of 185 species representing 69 genera. Seven new genera and 39 new species are described. The high diversity of taxa across the platform-to-basin transect shows the biogeographic differentiation and spatial ecological partitioning of conodonts through time. The taxonomy permits the refinement to the biostratigraphic zonation within two faunal realms for British Columbia that can be correlated with schemes elsewhere in North America and also internationally.

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 include Drepanoistodus latus and four new species left in open nomenclature assigned to the following genera: Walliserodus, Multioistodus?, Pseudooneotodus, and Belodina. The Midcontinent Realm zones recognized include, in ascending order, the Acodus kechikaensis, Oepikodus communis, Jumudontus gananda, Tripodus laevis to Plectodina aculeata zones, Phragmodus undatus and Gamachignathus ensifer? zones. Zonal species of the Atlantic Realm are Microzarkodina flabellum, Eoplacognathus suecicus, Baltoniodus variabilis, Pygodus anserinus, and Amorphognathus tvaerensis. The Silurian fauna, of lower diversity than the Ordovician fauna, is representative of the Distomodus staurognathoides and Pterospathodus amorphognathoides zones.

CONODONT FAUNA AND BIOSTRATIGRAPHY OF THE OUTRAM, SKOKI, AND OWEN CREEK FORMATIONS (LOWER TO MIDDLE ORDOVICIAN), WILCOX PASS, ALBERTA, CANADA

Abstract A collection of 60,886 conodonts was recovered from 141 samples of the Outram, Skoki and Owen Creek Formations (Lower to Middle Ordovician) that outcrop through the Wilcox Pass section, Jasper National Park, Alberta, Canada. This section represents the standard reference section for the Lower-Middle Ordovician of the Southern Canadian Cordillera. The well preserved fauna is assigned to 75 species representing 48 genera. The species are representative of both the Midcontinent and Atlantic faunal realms, but dominantly the former. Nine Midcontinent Realm zones are recognized in the upwards shallowing carbonate platform succession including the Scolopodus subrex, Acodus kechikaensis, Oepikodus communis, Jumudontus gananda, Tripodus laevis, Histiodella altifrons, Histiodella sinuosa, Histiodella holodentata, and Phragmodus “pre-flexuosus” zones. Zones recognized that are characteristic of the Atlantic Realm include Paroistodus proteus, Paracordylodus gracilis, Oepikodus evae, Paroistodus originalis, and Microzarkodina flabellum. A new genus, Filodontus, is proposed for elements assigned previously to the form genus “Scolopodus” filosus. A new species, Leptochirognathus wilcoxi, is described and one new species, left in open nomenclature, is assigned to Rossodus?.