Migration routes of the genus Buntonia Howe, 1935 (Ostracoda, Crustacea) during the Late Cretaceous–Paleogene in Africa

Abstract

Buntonia is a common genus in the Maastrichtian to Late Eocene basins of Africa. Analysis of similarity (ANOSIM), hierarchical clustering (HC), and non-metric multidimensional scaling (nMDS) were used to analyze the geographic pattern of Buntonia species based on the presence/absence matrix of 42 species. The Jaccard-based HC shows that the African countries can be subdivided into three main bioregions: North Africa (Algeria, Libya, Tunisia, Morocco, and Sudan), West Africa (Mali, Togo, Benin, Cote d’Ivoire, Senegal, Ghana, Gambia, Nigeria, Cameron, and Mauritania), and South Africa (Namibia and South Africa). ANOSIM indicated a non-significant difference between North and West African countries and between West and Southern Africa. However, a significant difference was found between North and Southern Africa (sequential Bonferroni corrected p < 0.01). These patterns are well-characterized also by both of HC and nMDS. Moreover, analyses of the stratigraphic ranges of the Buntonia species revealed a distinct range shift within the regions of the Guinean Gulf (Togo, Benin, and Cote d’Ivoire) through Senegal towards North Africa. The latter indicates two possible migration routes from West Africa to North Africa through the Trans-Saharan seaway and from the Atlantic to the Tethyan Sea. Migration from region to region played an important role in the distribution of the studied Buntonia species rather than origination of new species and/or extinction of existing species.