A Middle Devonian atrypid brachiopod fauna from the Cantabrian Mountains, northwestern Spain, and its stratigraphic significance

This paper records for the first time a rich atrypid brachiopod fauna from the Middle Devonian of the Cantabrian Mountains, Spain. A comparison of the Spanish atrypid fauna with that of Germany reveals a close similarity between the two. Even though the species are not identical, yet a comparison and stratigraphic evaluation has been made on the basis of external shape of the shells, ornamentation, etc. It is believed that the development of the Spanish species has been endemic or that the Spanish Middle Devonian sea was supplied with species immigrating from some place other than central Europe. On the basis of the distinct recession of Atrypa and the first appearance of the coarse ribbed species of Spinatrypa (Spinatrypa) a tentative Eifelian/Givetian boundary has been sought in the Portilla Formation of the Alba syncline between the rivers Luna and Bernesga, Prov. León, N.W. Spain. It is hoped that these findings would be correlated with other areas as well in the northwestern Cantabrian Mountains. The described and figured new species cantábrica is the third species of Spinatrypa (Invertrypa) hitherto known. Questions of its generic and subgeneric assignment and of the taxonomy and morphology of Spinatrypa (Invertrypa) are discussed. Sp. (Inv.) cantabrica (as well as Sp. (Inv.) fasciplicata and Sp. (Inv.) kelusiana) seems to be an important time marker of late Eifelian. By means of these three species, this time level and the geographic range of Spinatrypa (Invertrypa) can be traced over a distance of about 2200 km, from Poland over Germany, Belgium, and northern France to Spain.