The first true anomiid bivalve?

A new anomiid, here designated Eonomia timida gen. et sp. nov., is described from the Upper Bathonian and Oxfordian (Middle and Upper Jurassic) of England and Normandy. Its attachment to the substrate by pallial secretion, and the detailed structure of its ligamental area, distinguish it from later members of the family. Uncertainty about the taxonomic position of previously described pre-Cretaceous members of the family makes it a likely candidate for the earliest known anomiid. T HE Middle and Upper Jurassic rocks of southern England and Normandy constitute some of the best-known geological sections in the world. Their faunas have been studied and restudied by a succession of eminent palaeontologists and stratigraphers for more than 150 years; hence it was surprising to discover, at a number of different localities and stratigraphic horizons, common and well-preserved individuals of a distinctive species of bivalve mollusc which cannot be placed in any known Recent or fossil genus. The purpose of this paper is to describe the occurence, morphology, ecology, and evolutionary significance of these bivalves. All material is housed in the Oxford University Museum (Nos. OUM J 40184-40199 and OUM JZ 1782-1790).