Meso-Cenozoic Caribbean Paleogeography: Implications for the Historical Biogeography of the Region

摘要

Since the latest Triassic, the Caribbean started to form as a system of rift valleys within west-central Pangea, later evolving into a mediterranean sea where distinct volcanic and non-volcanic islands evolved. Since its very earl)' formation, this sea has been playing an important role controlling the historical patterns of ocean water circulation, moderating the world climate, and determining the possibilities of biotic exchange of the surrounding terrestrial and marine ecosystems. The formation of a Mesozoic marine seaway between western Tethys and the eastern Pacific, across west-central Pangea, has been postulated for the Early Jurassic (Hettangian-Pliensbachian) according to biogeographic considerations, but supporting stratigraphic data are lacking. Probably since the Bathonian but certainly since the Oxfordian, the stratigraphic record indicates that this connection was fully functional and the Circum-Tropical marine current was active. Overland dispersal between western Laurasia (North America) and western Gondwana (South America) was interrupted in the Callovian when the continents were separated by a marine gap. Later, a connecting land bridge may have been present during the latest Campanian/Maastrichtian (approx 75-65 Ma), and since the Plio-Pleistocene (2.5-2.3 Ma). Evidence for a precursor bridge late in the Middle Miocene is currently ambiguous. Since the formation of the first volcanic archipelago within the Caribbean realm at about the Jurassic-Cretaceous transition, volcanic islands, shallow banks, and ridges have been present in the paleogeographic evolution of the area. However, these lands were generally ephemeral, and lasted just a few million years. Only after the Middle Eocene (<40 Ma) were permanent lands present within the Caribbean realm, providing substrates for the formation and development of the present terrestrial biota.