Abstract
The detailed analysis of the dacryoconarids from the Vanes Beds (Abadia Formation) provided the means for determining the age of the mimosphinctid-bearing strata from the Lower Devonian of the Cantabrian Mountains. This study has evidenced the existence of two different stratigraphic intervals containing the most primitive ammonoids (Anetoceras Fauna). The lowest interval belongs to the upper part of the N. barrandei Biozone and to the N. elegans Biozone. The upper interval is slightly younger and belongs to the N. cancellata Biozone. The accurate dating of this beds with primitive ammonoids is of the prime interest, since it makes easier the correlation with contemporaneous successions from other areas of the N-Gondwana. On the other hand, as the mentioned beds are situated close to the potential Lower/Upper Emsian boundary, the establishing of their age will also help to the further subdivision of the Emsian. In this respect, it should be kept in mind that the International Subcommission on Devonian Stratigraphy (SDS) has recommended to select the Lower/Upper Emsian boundary in a level close to the base of the N. cancellata Biozone.
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