New information on olenelline trilobites from the Early Cambrian Sekwi Formation, Northwestern Canada

Abstract

A new species of olenelline trilobite, Nevadella keelensis, is described from the Early Cambrian (Cambrian Series 2, Stage 3) in the Sekwi Formation, Mackenzie Mountains, Canada. The difficulty in discerning between Nevadia Walcott, 1910 and Nevadella Raw, 1936 is discussed, and a revision of the two genera is suggested, particularly with the addition of Nevadella keelensis n. sp. A holmiid trilobite, perhaps conspecific with Esmeraldina rowei (Walcott, 1910), was also confirmed from the same locality. The E. sp. aff. rowei represents the narrow form of a species known for great variability in cephalic form. The trilobite material comes from a low diversity, shallow water, peritidal facies that was not sampled in previous studies of Cambrian fossils in the area, and could prove useful in facilitating biostratigraphic correlation across the Selwyn Basin and with other parts of Laurentia as well.