EARLY CRETACEOUS CEMENTING PECTINID BIVALVES

Large thick-shelled cementing pectinids, variously described as Prohin nites, are conspicuous, if not abundant, epifaunal bivalves in shallow marine facies deposited in a range of Tethyan and Southern Temperate locations during the Early Cretaceous. The relationships between these bivalves and Jurassic members of the genus Eopecten, some individuals of which were able to cement to hard substrata, have previously been unclear. The recent discovery of well preserved specimens of Prohinnit es in the Aptian Perna Beds Member of the Isle of Wight has allowed a re-examination of Early Cretaceous cementing pectinids and description of their morphology and shell microstructure. Comparisons with Middle and Upper Jurassic cementing Eopecten have shown that the Cretaceous Prohinnites are closely but not directly related. It is probable that these taxa represent multiple evolution pectinids. (C) 1996 Academic P ress Limited