The Lower Cretaceous Mesogean benthic ecosystems: palaeoecologic aspects and palaeobiogeographic implications
Abstract Douville's Mesogee was based on an organismic assemblage and therefore defined mainly as a palaeobiogeographic entity. The palaeoecologic analysis of Douville's Lower Cretaceous reference taxa, as well as that of a lot of other taxonomic groups, and the discussion on their palaeobiogeographic meaning, according to the concepts of modern marine biogeography especially the bathymetric/thermic relationships, result in the definition of three main organismic assemblages whose Mesogean significance is discussed. The key reference taxa and associated biota indicate that the definition of the Lower Cretaceous Mesogee implies characteristic palaeoenvironmental conditions. This definition, substantial for the whole Cretaceous, means that Mesogee is not simply a palaeobiogeographic entity but also an ecosystem corresponding to the area of distribution of warm, shallow-water carbonate platforms.