Trilobites de la familia Olenidae en el Ordovícico inferior (Arenigiano) de la Cordillera Oriental Argentina

Abstract

Olenid trilobites from the Acoite Formation (Arenigian) that crops out in the Argentine Cordillera Oriental are described and figured. Eight species are reported, three of which are new: Porterfieldia cuadrata sp. nov., Hypermecaspis occidentalis sp. nov. and Hypermecaspis chamarrensis sp. nov. Porterfieldia is reported from the Lower Ordovician of Argentina for the first time. Likewise, Saltaspis Harrington and Leanza had not previously been recorded in strata of early Arenig age of the Cordillera Oriental. These records significantly increase the diversity of the group in the Arenigian of the Cordillera Oriental. Olenids occur in moderately to highly diversified trilobite-dominated assemblages, accounting for transitional associations between the raphiophorid and the olenid community types.