Late Cretaceous paleobiogeography of Braarudosphaera bigelowii
Abstract The Late Cretaceous paleobiogeography of the coccolithophore Braarudosphaera bigelowii is reconstructed based on 331 stratigraphic occurrences and complemented by 307 neighboring absences. During the Cenomanian B. bigelowii was found throughout the European seaways, at the base of the North America Interior Seaway, at the paleo-Atlantic margin of South America, in the Neuquen Basin, on the southern tip of the Indian plate, and on the Kerguelen Plateau. During the Late Cretaceous, its range gradually expanded: northwards along the North Sea, into the North American Interior Seaway, eastwards through the interior European seaways, across central Russia, southeastwards into China, and along the Asian coast up to Japan. The Falkland Plateau appears to have played a pivotal role in the colonization of the eastern coast of South America, the Atlantic and Indian Ocean margins of Africa, Madagascar, India, western Antarctica, and Australia. By the end of the Maastrichtian, migration extended northwards towards the Arctic, but did not reach the northernmost regions of the North Atlantic. Because biogeographic information is scarce for the northern coast of South America, for several areas along the African margin, and for the overall Pacific coasts, it is difficult to resolve the biogeographic history in these areas. The presence of B. bigelowii could not be confirmed on the northern coast of South America or on the North Atlantic African margin. It is also not possible to ascertain whether the African margin facing the Indian Ocean was completely colonized by the end of the Cretaceous. Sparse observations suggest that the Pacific coast of North America was colonized by B. bigelowii during the Santonian. However, even though data suggests a subsequent northward colonization direction, it is not possible to accurately reconstruct the North Pacific migration paths of B. bigelowii between the Santonian and the Maastrichtian.