Silurian (Wenlockian) trilobites from Baillie-Hamilton Island, Canadian Arctic Archipelago

Abstract

Wenlockian trilobites representing at least 15 genera are reported from carbonate strata within the Cape Phillips Formation, Baillie-Hamilton Island. The collections are stratigraphically bounded by the graptolite Zones of Cyrtograptus murchisoni and Monograptus testis. The fauna is generically dominated by lichids, odontopleurids, and cheirurids. Scutelluids, phacopids, dalmanitids, and harpids are notable for their absence. At the familial level the fauna corresponds to one recently discovered from similar age beds of the Mackenzie Mountains, Northwest Territories. The limited quantity and fragmental nature of much of the silicified fauna precludes erection of many new taxa, although four new species described are: Sphaerexochus dimorphus, Dicranogmus skinneri, Hemiarges rohri, and Hemiarges mikulici. Dimorphic pygidia are interpreted as probable sexual dimorphs in Sphaerexochus dimorphus n. sp.