Palaeodiversity of Caribbean echinoids including new material from the Venezuelan Neogene

Abstract

The extensive Venezuelan coastline is very important for understanding the evolution of the Caribbean marine fauna. We report new fossil material collected from three Neogene fossil sites in the Falcon Basin and present the first diversity analysis of the known fossil echinoids from Venezuela and other Caribbean regions. Five species are reported for the first time from Venezuela. Each of the three fossil sites shows a different taxonomic composition, which may be a consequence of differing palaeoecological conditions during the Neogene. Furthermore, the environmental changes caused by the closure of the Central American Isthmus may also have played a role. The analysis of the Venezuelan echinoid fossil record, including the new herein described material, reveals three major diversity decreases and a maximal diversity peak in the Middle Miocene instead of the Eocene as it is the case in other Caribbean echinoid faunas. The first diversity decrease at the end of the Early Cretaceous, recognised by a gap in the fossil record, unfolds new research potential. The second one, around the Eocene-Oligocene boundary, is interpreted as an extinction event, as has been recognized for other echinoid and invertebrate faunas throughout the Caribbean. In contrast to other Caribbean invertebrate faunas, the cause of the third diversity decrease of echinoids throughout the Caribbean appears to be the beginning, instead of the end, of the closure of the Central American Isthmus. Although Venezuela plays a special ecological role in the Caribbean due to its seasonal upwellings, this study provides (1) a basis to better understand the fossil Venezuelan echinoid fauna, (2) a contrast to other Caribbean regions, and (3) insights into the Caribbean echinoid evolutionary patterns.