The Amoeboceras faunas of the Upper Calcareous Grit Formation (Jurassic, Upper Oxfordian) of North Yorkshire

Abstract

SUMMARY The Yorkshire Upper Calcareous Grit Formation consists of a sequence of sandstones, impure limestones and argillaceous siltstones ranging from 9 m to 20 m in thickness. Though generally poorly fossiliferous, individual horizons at certain localities can be remarkably fossiliferous, and have yielded some 370 cardioceratid and perisphinctid ammonites. Two localities, Newbridge Quarry near Pickering and Laysthorpe Quarry near Nunnington, are the most prolific source of the cardioceratid ammonite Amoeboceras in the Glosense Zone in Britain. Six species are described and figured, of which one, Amoeboceras newtonense, is new.