The occurrence of the hydrozoan genusCassianastraeafrom Upper Triassic (Carnian) rocks of Williston Lake, British Columbia, Canada

Abstract

Cassianastraeais an enigmatic colonial Triassic cnidarian first described as a coral but subsequently referred to the Hydrozoa. We report here the first occurrence in Canada of fossils we designate asCassianastraeasp. from the Williston Lake region of British Columbia. The specimens come from older collections of the Geological Survey of Canada, collected in Upper Triassic (Carnian) strata assigned to either the Ludington or Baldonnel Formations. While well known in reef associations of the former Tethys region,Cassianiastraeais relatively rare in North America. The Carnian Baldonnel Formation contains the earliest coral reefs from the North American craton and we suspect thatCassianastraeasp. also came from this reef association.