Late Cretaceous rotaliids (Foraminiferida) from the Western Tethys

During the global community maturation cycle starting at the Cenomanian- Turanian boundary and ending with the events at the K-T boundary, the rotaliid foraminifera produce for the first time in Earth History a considerable diversity of K- strategists that exhibit large shell sizes, complex umbilical structures and an important dimorphism of generations. In the Late Cretaceous Pyrenean Gulf four groups are distinguished. 1. Closest to the Cenomanian progenitor Rotorbinella mesogeensis (TRONCHETTI, 1981) are Rotorbinella campaniola n. sp. and Pyrenerotalia longifolia n. gen. n. sp. characterized by an increasing elongation of the folia. Iberorotalia n. gen. reicheli (HOTTINGER, 1966) belongs to the same group but produces a heavy ornamentation on the umbilical face that modifies and complicates the umbilical structure. 2. Orbitokathina with its species O. vonderschmitti HOTTINGER, 1966 and O. campaniana n. sp. are related to the Paleocene group of Kathina that is also present in the Caribbean Late Cretaceous. 3. The pararotaliids (with a toothplate, an umbilical structure that is controversial) remain conservative during the Late Cretaceous and produce only much later, in the Late Oligocene, larger foraminifera, namely the miogypsinids. 4. Calcarinella n. gen. schaubi (HOTTINGER, 1966) is considered to be closer to Calcarina than to Pseudorotalia or Lockhartia and therefore is transferred to the calcarinines. The large-sized rotaliids of the Late Cretaceous unfold their diversity in the Early Santonian, at the usual distance of about ten million years from the start of the maturation cycle, but their diversity and abundance is reduced later under the competition of the rising siderolitines and orbitoids during the Campanian-Maaestrichtian. ©2009 E. Schweizerbart'sche Verlagsbuchhandlung.