SCAPHORELLA, UN NUEVO GENERO DE TRIGONIIDAE (BIVALVIA) DEL JURASICO MEDIO DE ARGENTINA, CHILE Y ESTADOS UNIDOS DE AMERICA

Abstract

"The new trigoniid genus Scaphorella nov. from the andean Middle Jurassic of Argentina, Chile and the U. S. of Ameríca, with Trigonia leanzai Lambert (1944) as type species is described in this paper. The new genus ís characterized on the flanks by two distinctive series of tuberculate ribs, and on the area by transverse rrbbing, showíng some common features with Scaphotrigonia Dietrich and Myophorella Bayle, exhibiting as well clear affinities with the subgenus Trigonellina Parnes. In Argentina, Scaphorella leanzai (Lambert) was found in the Lajas Formation in -the localities of Los Pozones, Barda Negra sur and Chacaicó, Neuquén province, where it is associated with ammonites and bivalves of Bajocian and Early Lower Callovian age. In Chile the same taxa was recorded in La Negra Formation in the locality of Cerros Buena Esperanza, Antofagasta region, and it is assigned on the basis of their associated bivalves lo the Bajocian. In the northern hemisphere, Myophorella cf. M. argo (Poulton, 1979 non Crickmay) from the Middle Bajocian of Alaska and Oregon, U.S.A. is assigned to Scaphorella nov. and it is probably conspecifíc with the type species. ""Myophorella"" kruusei H. Leanza and Garata (1987) from the Bajocian of Neuquen is also included in Scaphorella nov. Therefore, the known range of the genus Scaphorella nov. in the argentine-chilean Andes and western U.S.A. coast ranges from the Bajocian to the early Lower Callovían,"