Late Ordovician Bivalvia Heteroconchia (Cycloconchidae and Glyptarcidae) from western Argentina
Abstract
Abstract On the basis of existing and new collections from northwestern Argentina (Sierra de Zapla and Sierra de Mojotoro) as well as from the Precordillera (San Juan Province), two new genera of the Superorder Heteroconchia Hertwig are erected. Specimens from the Santa Gertrudis Formation (Late Llanvirn-Early Caradoc, Quebrada del Gallinato, Sierra de Mojotoro) assigned to Cycloconchacf. C. oblongaFoerste were revised, and on the basis of new collections from the Capillas Formation (Sierra de Zapla) a new taxon of Glyptarcidae Cope, Zaplaellacapillaensisgen. and sp. nov., is erected. Poladontasanjuanina gen. and sp. nov. is proposed for unnamed, previously studied specimens of Cycloconchidae Ulrich from Early Caradoc pebbles contained in the basal diamictite of the Don Braulio Formation (Precordillera basin). Resumen. BIVALVIA HETEROCONCHIA (CYCLOCONCHIDAE Y GLYPTARCIDAE) DEL ORDOVÍCICO TARDÍO DEL OESTE DE ARGENTINA. En base a colecciones previas y recientes procedentes del noroeste argentino (Sierra de Zapla y Sierra de Mojotoro) y de la Precordillera (Provincia de San Juan) se definen dos nuevos géneros del Superorden Heteroconchia Hertwig. Se revisó el material de la Formación Santa Gertrudis (Llanvirniano tardío-Caradociano temprano), aflorante en la Quebrada del Gallinato (Sierra de Mojotoro) asignado previamente a Cycloconchacf. C. oblonga Foerste. Este material junto con ejemplares adicionales procedentes de la Formación Capillas (Sierra de Zapla) sirvió para la erección del nuevo taxón Zaplaella capillaensisgen. et sp. nov. incluido en la Familia Glyptarcidae Cope. Asimismo, se propone Poladonta sanjuaninagen. et sp. nov. para cycloconchidos provenientes de bloques de la diamictita basal de la Formación Don Braulio (Precordillera), de edad Caradociana temprana.Downloads
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