Palaeofloristics of Middle Pennsylvanian lyginopteridaleans in Variscan Euramerica

During Bolsovian times, the Lyginopteridales (Spermatophyta) had a very similar biogeographical distribution across Variscan Euramerica to that revealed by the Medullosales (Spermatophyta). However, this biogeographical pattern progressively breaks-down during Asturian and Cantabrian times, as the species diversity of the order declines dramatically. This decline was probably the result of being out-competed for resources by the reproductively more-sophisticated Callistophytales. There remains little direct evidence for marked climate changing occurring until middle or late Cantabrian times.