Comparación entre la fauna malacológica de las principales formaciones del Plioceno marino de Costa Rica, América Central

Abstract

This paper presents a list of the mollusks found and (already) described in the literature, in the Pliocene sedimentary formations of Costa Rica.
This formations are known as Montezuma Fm., Charco Azul Fm. and Rio Banano Fm. The first two are present in the Pacific Coast whereas the last one ocurrs in the Atlantic or Caribbean coast. The analysis of recent species in the faunas shows that these rank between 40 and 60 percent of the total, which is a good relation for Pliocene molluscan associations. 
The Pacific coast Formations show a majority of recent species typical for this coast, particularly in the Panamic province. Also they show a very low porcentaje of Caribbean species. The fauna of the Rio Banano Fm. is characterized by a great number of Caribbean recent species (83%) and a low number of Pacific ones (10%). This can be interpreted as a consecuence of the uplift to the region during the Pliocene.