Los braquiópodos del Coniacense (Cretácico Superior) de la plataforma norcastellana, e implicaciones en el origen y la evolución de la asimetría obligada en cyclothyris

Résumé

During the development of this research, the external and internal features, and the distributions of Coniacian brachiopods from the Northern Castilian Platform (Northern Spain) have been studied; especially from the sections of Villamartín, Turzo, Nidáguila, Basconcillos and Lastras (Southeastern part of the Cantabrian Range, Province of Burgos). Moreover, a revision of numerous European Upper Cretaceous brachiopod collections (e.g., d’Orbigny, 1842-1851; Coquand, 1860, 1862, 1879; Arnaud, 1877; Owen, 1962, 1988; Middlemiss, 1978) has contributed to improve some systematical, biostratigraphical and palaeobiogeographical questions, allowing to update taxonomically this group, including the description of new species and lectotypes. This update is especially relevant for the asymmetric representatives of the genus Cyclothyris M’Coy, 1844...