Objeto de conferencia
Upper Ordovician (Sandbian) gastropods from redeposited boulders in the Don Braulio Formation, Argentine Precordillera
Autor
Bertero, Verónica
Institución
Resumen
The glacigenic boulders from the Hirnantian Don Braulio Formation of the Argentine Precordillera contain a well preserved shelly fauna allowing to a better knowledge of brachiopods and bivalves, but gastropods remain undescribed. The purpose of this paper is to give a preliminary list of gastropods and to evaluate their paleobiogeographic affinities. The following taxa have been recognized: Tropidodiscus sp., Raphistoma sp., Clahtrospira aff. C. subconica Hall and Tetranota bidorsata Hall. Other contemporary coarse-grained boulders have yielded Bucania sp., Cyclonema sp., Clathrospira sp., Trochonema? sp., bellerophontids, platyceratids, Hormotoma-like forms, murchisonids and lophospirids indet. This material is not well preserved enough for accurate identifications. The genus Tropidodiscus Meek and Worthen has been proposed as a potential paleobiogeographical marker for the Mediterranean Province, and consequently for cold water environments. Tetranota bidorsata Hall and Clathrospira subconica Hall are common taxa in the Upper Ordovician Trenton Limestone. Such a mixture of faunas is consistent with the paleogeographic pattern of rhynchonelliform brachiopods, which display Mediterranean, Anglo-Baltic and Laurentian affinities. The studied gastropod assemblage includes mainly widespread taxa, lacking the marked endemism showed by coeval bivalves. Simposio I: 2º Simposio de bioestratigrafía y eventos del Paleozoico inferior Facultad de Ciencias Naturales y Museo