A New European Marsupial Indicates a Late Cretaceous High-Latitude Transatlantic Dispersal Route

The first record of an undoubted opossum-like marsupial from the Mesozoic of Europe indicates an invasion from North America at the end of Late Cretaceous (Maastrichtian). The new 66.1 million-year-old marsupial, Maastrichtidelphys meurismeti n. gen., n. sp., represented by a right upper molar, comes from the type Maastrichtian of The Netherlands. The Maastricht marsupial exhibits affinities with earlier (early Maastrichtian) North American herpetotheriids providing definitive evidence of a high-latitude North Atlantic dispersal route between North America and Europe during the latest Cretaceous. Previously, the first major interchange for marsupials was thought to have occurred nearly 10 million years later in the Eocene. The occurrence of this new marsupial in Europe implies that at some time during the latest Cretaceous, sea level and climatic conditions must have been sufficiently favorable to allow for such a high-latitude dispersal. The fragmentary remains of hadrosaurid and theropod dinosaurs, as well as boid snakes from northwestern Europe which have affinities with North American taxa help substantiate assumptions made by the occurrence of the herpetotheriid marsupial in Maastricht.