A new species of dicommopalla (acritarcha) from the middle Ordovician Simcoe group of southern Ontario, Canada

Abstract

Samples of mudstone and wackestone from the Middle Ordovician Gull River and Bobcaygeon formations of southern Ontario, Canada, yielded a new species of Dicommopalla herein designated as Dicommopalla rissae n. sp. Thus the total range of the genus Dicommopalla, which was previously Edenian to Rocklandian, is extended to older sediments of Blackriveran age. The distribution of the new species within these sediments suggests that it may have had a preference for shallow water lagoonal environments, but it is also found in association with acritarchs indicative of deeper water.