Washington State trigoniids (Bivalvia) from the conglomerate of Patterson Lake (Early Cretaceous)
Abstract
Despite more than 150 years of research on the Jurassic and Cretaceous trigoniid bivalves of the Pacific Coast of North America, little mention is made of Washington State trigoniids. In this study, five trigoniid species from the Methow Basin are documented from three sites in the Lower Cretaceous conglomerate of Patterson Lake (cPL). Three of the species, Yaadia whiteavesi, Columbitrigonia condoni, and Notoscabrotrigonia oregana, are well-known in the literature. The other two, Parvitrigonia n. gen. cooperi n. sp. and Earlpackardia methowensis n. sp. are undescribed rutitrigoniids. These identifications revise the faunal lists from previous geological studies of the Methow Basin and allow a middle Albian age assignment to the upper portion of the cPL.