Middle Devonian epicontinental ostracods from western Canada. 1. Palaeocopina

摘要

Diverse and well-preserved ostracod assemblages have been recovered from Middle Devonian (Eifelian - Givetian) sequences throughout western Canada, including the Yukon and Northwest Territories. About 110 species of the palaeocopid Suborder Palaeocopina Henningsmoen, 1953 are described taxonomically, some provided with formal names while others are left under open nomenclature. New taxa include: Adelphobolbina (Postadelphobolbina) n. subgen. (type species A. (P.) praeclara n. sp.), Sulcicuneus gemmqeern. sp., S sp. 308 forma cumgemmifer, S. sp. 818 forma pregemmifer, Urfiella(Mackenziella)triangula n. sp., Illativella triquetra n. sp., and Pseudoleperditia? vetusta n. sp. All faunal elements are indicative of relatively shallow-water environments. However, the sequence-stratigraphic evolution of this region left its stamp on the ostracode assemblages, which vary from high-diversity faunas in open-marine limestones to rare and low-diversity faunas in "restricted" carbonates. Some taxa are traceable to occurrences known in the United States (Michigan, western New York) and a few have Old World connections. However, many species, such as the representatives of A. (Postadelphobolbina) n. subgen., Mutulollina BECKER & BRAUN, 2006b, Falsogravia BECKER & BRAUN, 2006c, Fictohollina BECKER & BRAUN, 2006c, and U. (Mackenziella) BECKER & BRAUN, 2007b, are seemingly endemic for western Canada and have regional stratigraphic importance.