Paleobiogeography of late Early Cretaceous to Early Paleocene marine Ostracoda in Arabia and North to Equatorial africa

摘要

About 1270 marine ostracod species of Aptian to Early Paleocene age from Central, West, North and east Africa (inclusive Madagascar) ad well as the Arabian Peninsula and Pakistan/Western India have been examined on their spatial and stratigraphical distribution. Their paleobiogeographical relations have been examined based on the Jaccard-index. The results of these comparative studies are demonstrated on nine geographical maps for each stage (Aptian through Early paleocene) and four paleogeographical reconstructions including the assumed land/sea distribution for Cenomanian, Turonian, Maastrichtian, and Early Paleocene times. The major results are the recognition of an increasingly uniform pan-'South Tethyan ostracod province' (north and Northeast Africa and the Arabian Peninsula) from the Aptian to the Cenomanian. Due to the emergence of major parts of the Arabian Shield during the Turonian, this pan-South Tethyan bioprovince was split into a western 'Protobuntonia numidica ostracod province' (north Africa and Western Middle East) and an eastern 'Kaesleria ostracod province' (Eastern Arabia, south Iran, Somalia) since the Coniacian. While the proliferation of the phylogenetic lines of the ostracod genera and species of the South Tethyan ostracod province' towards the Protobuntonia numidica faunas into the Turonian-Coniacian was continuous, the newly developing genera and species of the Protobuntonia numidica and the Kaesleria provinces of the 'Senonian'-Early Paleocene had almost nothing in common. Although most of Northeast Africa and the Arabian Shield underwent strong subsidence during the Campanian-Maastrichtian combined with a widespread transgression, these strictly separated bioprovinces did not reunite or show clear faunal interrelationships during these times. The reasons for the described phenomena are probably largely to be sought in the paleoecological peculiarities of the regarded ostracod faunas (i.e. a relatively cooler water fauna in the Protobuntonia province (probably partially influence by upwelling) and a relatively warmer, tropical fauna in the Kaesleria province). However, the strict separation of these ostracod assemblages along a narrow N-S directed borderline running from Northeast Saudi Arabia across Jordan into Syria is thought to be highly unusual and to require further investigation, which could probably stimulate new paleo-oceanographical and paleogeographical considerations for the Late Cretaceous-Early Paleocene of Northeast Africa, the Middle East and Arabia.