Upper Marianian (Cambrian Series 2) trilobites from the Totanés–Noez area (Central Iberian Zone, Toledo province, Spain): systematics and intercontinental correlation

Abstract

Marianian (Cambrian Series 2) trilobites from the area between Totanés and Noez (Central Iberian Zone) are described and their biostratigraphical significance is discussed. The trilobites come from eight localities and can be divided into two main assemblages: the first is characterised by Serrodiscus bellimarginatus, Chelediscus cf. garzoni, Atops calanus, Pseudatops reticulatus and indeterminate polymeroid trilobites. The second assemblage consists of Serrodiscus bellimarginatus, Triangulaspis cf. fusca, Andalusiana palaciosi n. sp., Termierella totanesensis n. sp. and Acanthomicmacca sp. Both fossil associations indicate a late Marianian age in the regional stratigraphic scheme for the Cambrian of the Iberian Peninsula, as Serrodiscus, Chelediscus and Pseudatops have been recorded from the upper Marianian substage, while Triangulaspis, Andalusiana, Termierella and Acanthomicmacca are indicative of the middle to upper Marianian. The taxa considered here have regional and intercontinental correlation potential. The presence of the globally distributed genus Serrodiscus allows correlation in the Cambrian Series 2. The first assemblage, composed of Serrodiscus, Chelediscus, Atops and Pseudatops, has been reported from the Ossa-Morena Zone, Avalonia, Laurentia, Baltica and Siberia, improving the correlation between these regions. The second assemblage of Andalusiana, Termierella, Triangulaspis and Serrodiscus is comparable to other assemblages from the Ossa-Morena Zone, the Iberian Chains and Morocco, with Triangulaspis also reported from Newfoundland and Siberia. In addition, the proposal of the ISCS regarding the co-occurrence of Hebediscus, Calodiscus, Serrodiscus and Triangulaspis as a potential marker for the base of the Cambrian Stage 4 may imply that the upper Marianian of Iberia could be approximately correlated with the base of this stage.