Cretaceous Continental Bridges, Insularity, and Vicariance in the Southern Hemisphere: Which Route Did Dinosaurs Take?

The history of biota distribution in the southern hemisphere represents a fascinating and strongly debated argument. The sequential break-up of Gondwana was indeed responsible for physical barriers that precluded dispersal event, and therefore phylogenies? Did different organism had the opportunity for dispersal episodes through recently claimed continental bridges? When geographic and environmental conditions were suitable for active diffusion during the Mesozoic? Among the most relevant taxa that inhabitant the southern landmasses in the Cretaceous period are dinosaurs. Their vast stratigraphic and geographic occurrence is intimately linked to the evolution of Gondwana and recent discoveries from all southern landmasses greatly challenged several vicariant models. In this study are summarised the most significant geological, palaeogeographic, palaeontological and phylogenetic data on Cretaceous Gondwanan dinosaur evolution, with particular emphasis on the ephemeral land bridges that constitute the bulk of the recently developed biogeographic models. A comparison between different datasets suggest that a complex and sequential mix of vicariance and dispersal patterns characterized the distribution of dinosaurian faunas in the Cretaceous. In particular, this study dispute the role of ephemeral intercontinental connections for biota dispersal in the Late Cretaceous and support an earlier peak in dinosaur distribution