Shell microstructure and variability of cell imprints of the mantle outer epithelium in the genus Suiaella Moisseev (Brachiopoda, Rhynchonellida) from the Lower Cretaceous of Crimea

Resumo

The shell microstructure of the Lower Cretaceous Suiaella weberi Moisseev, 1949 (superfamily Norelloidea) from the Lower Barremian of Crimea is studied for the first time. The fibers of Suiaella are shown to differ strongly in size and outline of cross section from the fibers of the superfamily Rhynchonelloidea. Suiaella is shown to differ from rhynchonellids of the superfamily Basilioloidea in the presence of straight or slightly curved fibers and absence of twisted fibers and overlapping adjacent fibers within one and the same bundle, it also differs in the presence of capillation and fine ribbing. Numerous cell imprints of the mantle outer epithelium have been found in fossil Norelloidea for the first time.