Biogeographical patterns of Ordovician ostracods

摘要: Abstract The biogeography of marine shelf ostracod genera is analysed for two Ordovician time slabs, the earliest Late and terminal Ordovician, that have been considered to reflect comparatively warmer cooler global climate states, respectively. earlier slab equivalent Nemagraptus gracilis graptolite interval (centred about 460 Ma), defined as total range eponymous species. Hirnantian comprises Normalograptus extraordinarius persculptus biozones (445.6–443.7 Ma). dataset consists 160 taxa from 24 early localities 86 10 localities. Ordination variation partitioning analyses show patterns in distribution are largely related palaeocontinental affinity samples a lesser degree palaeolatitude. Some decrease provincialism can be suggested Hirnantian, although limited this interval.