Givetian Brachiopod faunas of the Palentian Domain (N Spain).

Abstract

The origin, evolution, structural and stratigraphical features of the Palentian Domain (Cantabrian Mountains, N Spain) are summarily described. The boundaries of the Givetian succession (ca. 40 m thick) in that area are established from previously known conodont and ammonoid data. The base of the Givetian is situated in the upper part of the Gustalapiedra Formation, at the base of the La Pedrosa Member. The upper Givetian boundary is situated at the top of the lower calcareous interval of the Cardaño Formation. Middle Devonian brachiopods are scarce in the Palentian Domain. In fact no Givetian form has been cited in the area until now. In this paper nine brachiopod species (three new) of the Givetian interval are described and figured: Skenidium cf. polonicum, Rhyssochonetes aff. douvillei, Prodavidsonia havliceki n. sp., Bifida aff. lepida, Ambothyris cf. infima, “Pyramidalia” palentina n. sp., Cingulodermis sotoana n. sp., Parastringocephalus cf. dorsalis, and Ense andrea. The genera Skenidium, Rhyssochonetes, Ambothyris, Cingulodermis, Parastringocephalus, and Ense are cited in Spain for the first time. Parastringocephalus is moreover the first stringocephaline found in Palencia. “Pyramidalia” palentina n. sp. is an impunctate form provided with a nearly complete symphytium, a delthyrial plate and short dental plates; these features separate the genus Pyramidalia both from Cyrtinaella and Thomasaria with which the former genus has sometimes been synonymised. Near the base of the Cardaño Fm. a coquina with thousands of specimens of Ense andrea has been found. This coquina could represent the area of the famous “Pumilio” Event, described previously from Germany, France and North Africa. The Spanish Ense andrea specimens are endopunctate and a sectioned shell shows a centronelliform brachidium. The terebratulid nature of the species is certain and the features referred to above and the external morphology of the shell are closer to the Subfamily Adreninae than to the Subfamily Mutationellinae where Ense had previously been tentatively included.