A false aciculariacean alga and its origin: an example from the Late Jurassic of the Northern Calcareous Alps, Austria

Abstract

Slightly curved calcitic plates with marginal pores recalling an aciculariacean alga are common in Late Tithonian reefal platform margin deposits of the Plassen Carbonate Platform of the Northern Calcareous Alps of Austria. Illustrated also from the Western Carpathians, these forms were assigned to the genus Acicularia, e.g., Acicularia elongata Carozzi. It is demonstrated that these algal parts are not reproductive caps of polyphysacean algae (formerly known as acetabulariaceans), but represent sections through scattered articles fragments of the dasycladalean alga Neoteutloporella socialis (Praturlon), more precisely the proximal parts of the laterals. This alga formed reefal bushes at the platform margin near-by to coral-stromatoporoid patches. The characteristic aciculariacean algae recalling fragments occur in bioclastic packstones, a facies adjacent to these dasycladalean algal microreefs.