A middle cenomanian coral fauna from the northern calcareous alps (Bavaria, Southern Germany) - New insights into the evolution of Mid-Cretaceous corals

Abstract

In the Northern Calcareous Alps, relics of a formerly widely distributed shallow marine facies belonging to the Branderfleck Formation (Upper Albian to Early Turonian) crop out and contain locally abundant corals. The fauna described here derives from Middle Cenomanian sediments. It encompasses 39 species in 25 genera, belonging to seven scleractinian and one octocorallian order. One genus and two species are described as new. The fauna that was formerly located at the northern part of the Apulian plate (Austroalpine unit), south of the Penninic ocean, shows palaeobiogeographic relationships to Cenomanian faunas from the Pelagonium, the Aquitanian Basin, and the Bohemian Basin, indicating stronger connections to Tethyan than Boreal faunas. The fauna also shares species with Aptian and Albian, as well as Late Cretaceous faunas. Ten genera experienced a range extension; five genera have their last occurrence in the Middle Cenomanian fauna, and five genera their first occurrence. The fauna has an intermediate position between the Early Cretaceous and the post-Cenomanian corals showing that the faunal turnover at the Cenomanian/Turonian boundary was not marked by the sudden appearance of new faunal elements, but the disappearance of taxa. Many faunal elements that constitute post-Cenomanian faunas already existed in the Cenomanian but were very rare.