Marok A., Sebane A., Mekahli L., Elmi S. (2007) Quantitative Biogeography of the Upper Aalenian-Lower Bajocian Ammonites (Western Tethys): Application of the Multivariate Methods // Online Journal of Earth Sciences. V.1. no.2. P.113-118
In order to quantify the biogeographic dynamics of ammonites faunas of Upper Aalenian-Lower Bajocian, 9 areas located in Western Tethys were analyzed by the multivariate method (Principal coordinate analysis and calculating similarity index and distance). The results obtained reveal the following facts:
-the stability and resemblance during the time of faunas of the Betic Cordillera, Iberian Cordillera, central High Atlas and the Lusitanian basin,
-the fluctuation starting from the Laeviuscula zone of Dorset-Somerset, the basin of South-east of France and the folded Middle Atlas.
This fluctuation is controlled by several factors: paleotemperature, eustatism, paleogeography, and trophic conditions, the isolation of faunas of Beni Snassen and Umbria-Marche Apennines.