Paleobiogeography of Paleogene larger Foraminifera from the Mediterranean Tethys to the western Pacific using Parsimony Analysis: a preliminary attempt.

Larger Foraminifera are a diverse and much investigated group, with a wide stratigraphic and paleobiogeographic distribution. The present work focuses on the Paleogene larger Foraminifera from the Mediterranean Neotethys and adjacent basins the Middle East, the eastern margin of Africa, SE Asia and the western Pacific domain. Aim of the present study is to discover whether using the existing larger foraminiferal evidence it is possible to discover historical patterns of relationships of the biota from the sample areas. Data matrices of taxonomic units and sample areas were compiled for five time intervals: Thanetian, Ilerdian, Middle Eocene, Priabonian and Rupelian. Among the various methods currently employed in paleobiogeography, Parsimony Analysis of Endemism was chosen because it allows to infer in cladistically unresolved groups the closeness of the biota of each sample area in respect to others. The method produces cladograms of sample areas which can he interpreted in terms of relative recency of biotic contact. However; a major constraint using this method is that taxa unique to a single sample area are uninformative. The integration of the available evidence on paleogeography, paleoclimatology and paleoecology suggests possible hypotheses to explain the obtained cladograms different diversities and taxonomical composition of the larger foraminiferal assemblages, although sampling and taxonomy may introduce paleontological artifacts. The preliminary data base of 335 operative taxonomic units may be expanded and represents a flexible tool for further studies.