Microcrinoids (Roveacrinidae) from the middle–upper Cenomanian Grey Chalk Subgroup, Dover (Kent, United Kingdom): biostratigraphy and re-evaluation of cup structure in roveacrinids

Abstract

New material of Roveacrinidae from the middle–upper Cenomanian Grey Chalk Group of the Kent coast (Folkestone-Dover) is described. The fauna includes 10 taxa, including a new genus and species ( Dubrisicrinus minutus) and three new species ( Styracocrinus shakespearensis, Roveacrinus aboudaensis and Dentatocrinus serratus). The biostratigraphical significance of roveacrinid faunas is placed in a global context, and it is demonstrated that the roveacrinid zone CeR5, previously recorded only from Morocco, is approximately equivalent to the upper middle Cenomanian Acanthoceras jukesbrownei ammonite Zone, and zone CeR6 – to the Calycoceras guerangeri ammonite Zone. The new material also provides novel information on the cup structure of roveacrinids, which is reviewed and placed in a phylogenetic context.