Adaptive morphologies of the brachiopod fauna from Danian coral mounds at Faxe, Denmark

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Only few of the brachiopod species that lived in the Late Cretaceous Chalk Sea of northern Europe survived the mass extinction at the Cretaceous–Paleogene boundary. However, a rich brachiopod fauna rapidly evolved from the survivors and most of the vacant niches were filled in by the middle Danian when a large cool-water, subphotic coral-bryozoan mound complex was developed at Faxe in the eastern part of the Danish Basin. The brachiopod fauna of the complex comprises 17 species dominated by micromorphic species of similar types as those known from the Upper Cretaceous, Maastrichtian chalk from the same region. All species are found in the coral mound facies and six of the species are restricted to this facies. Large-sized species are rare both in terms of species numbers and abundance. One species is adapted to a life between the branches of the cool-water hexacorals Dendrophyllia candelabrum and Oculina becki. Secondarily free-living species are close to absent. This is in contrast to the Maastrichtian chalk fauna where this group includes 10 species (~24% of the total brachiopod fauna). The otherwise great similarity in morphological adaptations in the brachiopods from the Maastrichtian chalk and the Danian coral mounds is remarkable and somewhat surprising as the latter almost lacks soft substrates. The Danian brachiopod fauna essentially represents a continuation of the Maastrichtian fauna, but in a very different habitat. The similarity between the two faunas is explained by the abundance of small, hard substrates, notably bryozoans in both environments. The brachiopods from Faxe are one of the very few ancient examples of a rich brachiopod fauna from a coral mound environment.

TidsskriftPalaeogeography, Palaeoclimatology, Palaeoecology
Antal sider15
StatusUdgivet - 2019

ID: 230201205