Temperature and nutrient controls of coralline algal and larger foraminiferal dominated Paleogene Tethyan carbonates

This study is based on facies and diversity patterns of late Eocene (Priabonian), early Oligocene (Rupelian) and late Oligocene (Chattian) LF and CCA communities occurring in neritic carbonate settings from the northern margins of the Western Tethys in northeastern Italy. Recent taxonomic re-assessments of coralline algae have shown important differences in species diversity from the Priabonian to the Chattian. During the Priabonian and the Chattian, melobesioids and mastophoroids are diverse and abundant, sporolithaceans are present with a moderately richness, Lithophylloideae are absent. During the Rupelian, although the corallines as a carbonate producer are very prominant, the diversity as such is markedly lower and is restricted to few melobesioid species. We discuss possible causes for these mid-latitude shallow-water carbonate benthic communities. We suggest that evolutionary and extinction events together with global and regional changes in temperature and trophic resources provide the key for understanding these dramatic changes in floral and faunal diversities.