Echinoderms from the upper Miocene Paraná Formation of Argentina

Abstract

Until now, the only fossil echinoderm described from the upper Miocene Paraná Formation of Argentina was the scutelliform Monophoraster duboisi. Here, we substantially increase this diversity by recording the ophiuroids Ophiocoma sp. and Ophiothrix sp., together with irregular echinoids including an immature indeterminate neognathostome, Abertella sp., Amplaster alatus, and Amplatser ellipticus. This revised taxonomic richness is concordant with a warm-water shoreface depositional environment. Our new records of Amplaster and Monophoraster represent the most northerly occurrences of their known geographic range. Likewise, we extend the Argentine distribution of Abertella some 1500 km further north, and identify the first upper Miocene example of the genus. The Argentine Paraná Formation echinoderm assemblage is thus similar to that from the coeval Camacho Formation of Uruguay. Sergio Martínez* [smart@fcien.edu.uy], Universidad de la República Facultad de Ciencias, Iguá 4225, 11400, Montevideo, Uruguay; Leandro M. Pérez [pilosaperez@gmail.com], CONICET, División Paleozoología Invertebrados, Museo de La Plata, Paseo del Bosque s/n, 1900, La Plata, Argentina; Claudia J. del Río[claudiajdelrio@gmail.com], CONICET, Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR, Ciudad Autónoma de Buenos Aires, Argentina.