Chapter 22 Testing Silurian palaeogeography using ‘European’ ostracod faunas

Abstract

Abstract The distributions of representative European and eastern North American species of the three major ostracod groups present in the Silurian independently support the standard palaeogeographical reconstructions of the ‘North Atlantic’ region for that time period. A range of assumed benthic, biostratigraphically key palaeocope and podocope ostracods show a provincial distributional pattern that characterizes a ‘European’ ostracod faunal province which reflects the amalgamated palaeoplates of Avalonia and Baltica. By contrast, representatives of the low-diversity, late Silurian, supposedly pelagic myodocope ostracod fauna from the UK, France, the Czech Republic, Sardinia and other locations globally seemingly have much wider dispersal capacity that includes, for example, trans-(Rheic)ocean locations on the Avalonia, Baltica, Armorica (West Gondwana) and Perunica palaeoplates. That there was an apparent major barrier to the migration of supposed benthic but not pelagic ostracod faunas strongly supports the notion of the presence of the Rheic Ocean and adjacent palaeocontinents. Comparable provincial and trans-oceanic distributional patterns are evident amongst Recent benthic and pelagic ostracods. The ostracod faunas of Avalonia/Baltica seemingly remained essentially distinctive, at least at species level, from those of the remainder of the Laurentian plate in the Silurian, but the reason for this is uncertain.