Early silurian brachiopods and biostratigraphy of the Hudson Bay lowlands, Manitoba, Ontario, and Quebec

Abstract

Articulate brachiopods of the Llandovery rocks of the Severn River, Ekwan River and Attawapiskat formations of the Hudson Bay Lowlands comprise 35 genera and 50 species, including 18 new species: Severella pinnigera, Gypidula rudiplicativa, Rhytidorhachis guttuliformis, Rostricellula subtilicostata, Microsphaeridiorhynchus hercostomaticum, Hercotrema spissicostatum, Meifodia discoidalis, Atyrypoidea praelingulata, Atrypopsis severnensis, Parmula hemisphaerica, Merista rhombiformis, Whitfieldella pygmaea, Whitfieldella sulcatina, Howellella porcata, Alaskospira fabiformis, Dalejina striata, Eoplectodonta (Eoplectodonta) hudsonensis, and Protochonetes harricanensis. The species of Alaskospira, Atrypoidea and Merista represent unusually early appearances of these genera. The biohermal complexes of the Attawapiskat Formation provided a great diversity of environments. Some species with small shells seem to have occupied specialized and protected niches within the complexes, whereas large, thick shelled species occupied open water environments. Three brachiopod assemblage zones can be recognized. The Virgiana decussata Zone (dominantly pentamerids) is succeeded by the Hercotrema winiskensisþStegerhynchus borealis Zone (dominantly rhynchonellids). Above, the Pentameroides septentrionalisþLissatrypa variabilis Zone has a very varied fauna with abundant pentamerids and spire-bearers. Species diversity increases from 6, to 15, and to 36 species in the three zones. The changes in diversity and in taxonomic composition were probably related to the changes in environments during the Early Silurian transgression from dominantly intertidal and lagoonal to dominantly subtidal and reefal. Correlations with successions on Anticosti and Manitoulin islands indicate that the Severn River Formation is latest Rhuddanian to late Aeronian in age, the Ekwan River Formation is Telychian, and the Attawpiskat Formation is late Telychian. Comparison with the outcrop succession of southern Manitoba indicates correlation of the basal Severn River Formation with the Fisher Branch Formation; the remainder of the Severn River Formation with the Moose Lake or ``Inwood'' (sensu McCabe), Atikameg, and East Arm formations; and the Ekwan River and the Attawapiskat Formation with the Cedar Lake Formation, but with the uppermost Attawapiskat being slightly younger.

Global diversity and endemism in Early Silurian (Aeronian) brachiopods

“…(e.g. ) monographed the brachiopods from the Hudson Bay Lowlands area of northeastern Canada, but there are no endemic genera. Jin & Chatterton () comprehensively described the faunas from the Avalanche Lake area of SW district of Mackenzie, NW Canada, where although the detailed correlation within the Llandovery is poorly constrained, there appear to be 11 Aeronian genera, none endemic.…”

Late Ordovician-Early Silurian conodont biostratigraphy and thermal maturity, Hudson Bay Basin

“…Norford (1971) and demonstrated that the uppermost beds of the Red Head Rapids Formation may be early Llandovery in age, but it has not been proven. Some previous studies documented that this disconformity represents the missing early Llandovery strata (Le Fèvre et al, 1976;Norris, 1993b;Jin et al, 1993). Some previous studies documented that this disconformity represents the missing early Llandovery strata (Le Fèvre et al, 1976;Norris, 1993b;Jin et al, 1993).…”

Introduction to the Special Issue commemorating the 30th anniversary of the Royal Tyrrell Museum of Palaeontology, with a summary of the museum’s early history and its research contributions

“…Taxonomic, descriptive, systematic, and similar publications involving one or more Royal Tyrrell Museum of Palaeontology (RTMP) authors. Johnston and Goodbody (1988), Hall and Neuman (1989*), Johnston (1991Johnston ( , 1993Johnston ( , 1996, Jin and Lenz (1992), Norford (1992, 1996), Jin et al (1993Jin et al ( , 1995, Chatterton (1996, 1997), Johnston and Collom (1998) • Turtles (excluding marine turtles): Brinkman and Nicholls (1991*, 1993a*, 1993b*), Brinkman and Peng (1993a, Brinkman et al ( , 2000Brinkman et al ( , 2008Brinkman et al ( , 2010Brinkman et al ( , 2012bBrinkman et al ( , 2013b, Peng and Brinkman (1993) Wu et al (1994Wu et al ( , 1996aWu et al ( , 1996cWu et al ( , 1996dWu et al ( *, 2001aWu et al ( *, 2001b.…”