Evolution of Caribbean echinoderms during the Cenozoic: moving towards a complete picture using all of the fossils

Abstract

In the Antillean region, collecting bias towards complete tests has engendered a lop-sided view of the diversity of the echinoderms through time. Crinoids, asteroids and ophiuroids, as well as certain echinoid groups, are widespread as fossils, but are only preserved as disarticulated or broken fragments that have commonly been ignored in studies of faunal diversity. Utilization of these disarticulated remains and collection of specimens from units that have hitherto been considered to lack common fossil echinoderms (such as the Plio-Pleistocene of many islands) is resulting in a more consistent synthesis of their regional diversity during the Cenozoic. Both echinoids and stalked crinoids show distinctive faunal changes following the Eocene–Oligocene extinction events, with the roots of their modern components appearing in the region at that time, at least at the generic level. In contrast, distinctive asteroid species that are recognised from the Oligocene do not appear to have persisted into the later Cenozoic of the region. Incorporation of data from disarticulated elements commonly indicates that regular echinoids were at least as diverse as irregular echinoids. Some taxa that are common in the Caribbean at the present day, such as diadematoids, that apparently lacked a recognisable fossil record due to taphonomic factors, are recognised from throughout the Cenozoic on the basis of distinctive disarticulated ossicles.