Fig. 2. A in First record of chambered hexactinellid sponges from the Palaeozoic

Fig. 2. A. Chronostratigraphic chart, showing Devonian lithostratigraphic units of Asturo-Leonese facies that have been defined in the regions of Asturias (northern part of the Cantabrian Zone) and León (southern part of the Cantabrian Zone). Absolute ages based on Gradstein et al. (2004). Stratigraphic subdivision of the La Vid Group according to Vilas Minondo (1971) and Vera de la Puente (1989), but subdivision by Keller (1988) is also shown. B. Simplified stratigraphy of La Vid Group in relation to sea-level development (based on Keller and Grötsch 1990) showing location of studied interval of Valporquero Formation. Modified after Fernández et al. (2006).