Arenaceous foraminifera from the Llandovery/Wenlock boundary beds of the Wenlock Edge area, Shropshire

Abstract

Abstract. Several thousands of specimens of arenaceous foraminifera have been collected from two sections in Shropshire that span the Llandovery/Wenlock boundary. Preservation in limestone samples is superior to that in shales, but both lithologies yielded abundant specimens. The uppermost Purple Shales, of Llandovery age, contain numerous Ammodiscus exsertus, together with Webbinelloidea tholus, Psammosphaera cava, Hemisphaerammina and Hyperammina. A faunal change occurs close to the base of the Wenlock, with the lower beds of the Buildwas Formation containing rather fewer foraminifera; assemblages here are dominated by Hyperammina, Lagenammina and Lituotuba? This event probably reflects a change in sea-floor environment, with habitats favoured by epifaunal encrusters and browsers contracting at the end of the Llandovery.