Mohawkian (Upper Ordovician) conodonts of eastern North America and Baltoscandia

Abstract

A collection of 57,877 conodont elements that includes 39 species representing 30 genera was made from the upper part of the Phragmodus undatus Zone and the lower part of the Plectodina tenuis Zone (late Turinian–early Chatfieldian). Conodont samples were collected from 30 sections in eastern North America and Baltoscandia, where the P. undatus–P. tenuis Zone boundary projects into B. alobatus Subzone based on K-bentonite bed correlation. Elements previously assigned to form-species of Oistodus are shown to be apparatus associates in coniform apparatuses of Besselodus. Pseudobelodina manitoulinensis new species is described and the apparatus-based taxonomy of Scyphiodus primus and Staufferella polonica are proposed.

Carbon cycling across the southern margin of Laurentia during the Late Ordovician

“…The conodont biostratigraphy for the Red Mountain section that was reported by Leslie (1995Leslie ( , 2000 was confirmed by the additional collections from this study (Fig. 4).…”

“…This fauna is indicative of the Ph. undatus zone, and it is typical of shallow-water, calcareous mudstone-dominated successions traditionally assigned to the Black River Group throughout much of eastern North America (Leslie, 2000). At 10.5 m above the Millbrig K-bentonite, the Erismodus and Curtognathus species disappear, and P. gracilis, Plectodina sp., Apheognathus sp.…”

“…All of these sections are north of the Helena trust fault (Fig. 2) and contain the Deicke and Millbrig Kbentonites (Kunk and Sutter, 1984;Haynes, 1994;Kolata et al, 1996;Leslie, 2000). The Deicke and Millbrig K-bentonite are well defined in Alabama based on differences in phenocryst mineraology (Haynes, 1994).…”

“…undatus elements were recovered from Gadsden, conodont yields were relatively low (Hall et al, 1986;Leslie, 1995) and the conodont fauna recovered is consistent with the Ph. undatus Zone (Leslie, 1995(Leslie, , 2000.…”

The Upper Ordovician trilobiteRaymonditesSinclair, 1944 in North America

“…D, M indicate the positions of the Deicke and Millbrig K-bentonites, respectively. Lithostratigraphy and correlation of the successions of Wisconsin, Illinois and Missouri are modified from Larson (1951), Templeton and Willman (1963), Leslie (2000), and Metzger and Fike (2013); ranges of species are based on DeMott (1987) and unpublished field data. Lithostratigraphy and correlation of the successions of Ontario and New York are modified from Kay (1937), Liberty (1969), Salad Hersi andDix (1999), Leslie (2000), Brett and Baird (2002), Mitchell et al (2004); ranges of species are based on Wilson (1947) from somewhat older strata ("Leray beds"; Wilson, 1947, p. 19) that are probably equivalent to the upper Gull River Formation.…”