Palaeobiogeography and evolution of mammals and other terrestrial vertebrates from the Upper Jurassic and Lower Cretaceous of Central Europe

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The Late Jurassic and the Early Cretaceous were key periods for theevolution of terrestrial vertebrates which was, among others, triggered by theemergence of angiosperm plants. The Jurassic mammal faunas weredominated by stem mammals such as docodontans and morganucodontans,and typical Mesozoic crown mammals such as eutriconodontans,multituberculates, and dryolestidans. Except for multituberculates, theseexperienced a decline during the Cretaceous and were replaced by"symmetrodontans" and tribosphenic stem therians (predecessors of modernmammals). The evolutionary history of amphibians is similar, where stemsalamanders were successively replaced by modern forms (lissamphibians).Localities yielding Late Jurassic and Early Cretaceous terrestrial vertebratesand escpecially mammals are rare in Europe and are hitherto restricted tothe western and southwestern part of that continent. The localitiesLangenberg Quarry at the northern rim of the Harz mountains (LowerSaxony) and Balve in the Sauerland (North Rhine-Westphalia) provide forthe first time insight into the evolution of Late Jurassic (Kimmeridgian) andEarly Cretaceous (Barremian-Aptian) mammals of Central Europe.Mammals have been reported from the Langenberg Quarry for the first timein 2015, and the Balve locality has been discovered in 2000. Besidesdinosaurs such as the dwarfed sauropod Europasaurus and othervertebrates the Langeberg has yielded teeth of a large morganucodontid anddocodontans (stem mammals), as well of multituberculates and dryolestids(crown mammals). In Balve remains of three major mammalian clades havebeen found so far, multituberculates, "symmetrodontans", and dryolestidans.The discovery of two mammalian mandibles and of articulated postcranialbones of dinosaurs underlines the potential of the Balve locality for thediscovery of more complete material. The undescribed two dryolestid taxafrom Balve are among the youngest in the Northern Hemisphere andindicate that dryolestidans were more diverse in Europe in the EarlyCretaceous than anticipated so far. This will allow to test an earlierforwarded hypothesis that predominant pretribosphenic dryolestidansdelayed the emergence of tribosphenic mammals (stemlineagerepresentatives of modern mammals with crushing tooth function) in Europe.Both localities are an important bridge between the western European andthe central and eastern Asian terrestrial vertebrate assemblages.Furthermore phenomena of insular isolation on the Late Jurassic-EarlyCretaceous European Archipelago can be studied, such as gigantism in thelarge morganucodontan Storchodon (together with dwarfism inEuropasaurus) or the late survival of taxa (possibly Jurassic synapsids;Cretaceous dryolestidans). Both localities for the first time provide insightinto a crucial evolutionary phase of mammals in Central Europe.