Seirocrinus subangularis(Miller, 1821), a Pliensbachian (Lower Jurassic) crinoid from the Fernie Formation, Alberta, Canada

Abstract

An almost complete specimen of the pentacrinidSeirocrinus subangularis(Miller, 1821) is described from the Red Deer Member of the Fernie Formation in the Rocky Mountains of central-western Alberta. Associated ammonites representing the Stokesi Subzone of the Margaritatus Zone indicate a Late Pliensbachian (Early Jurassic) age for the specimen. Taphonomic features suggest preservation in soft muds on a quiet, oxygen-deficient seafloor, so that the lower surface is preserved intact while ossicles on the exposed upper surface became disarticulated and were slightly disturbed. This occurrence in western Canada represents a major extension of the geographic range of the species.