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

In the Antillean region, collecting bias towards complete tests has engende red a lop-sided view of the diversity of the echinoderms through time. Crin oids, asteroids and ophiuroids, as well as certain echinoid groups, are wid espread as fossils, but are only preserved as disarticulated or broken frag ments that have commonly been ignored in studies of faunal diversity. Utili zation of these disarticulated remains and collection of specimens from uni ts that have hitherto been considered to lack common fossil echinoderms (su ch as the Plio-Pleistocene of many islands) is resulting in a more consiste nt synthesis of their regional diversity during the Cenozoic. Both echinoid s and stalked crinoids show distinctive faunal changes following the Eocene -Oligocene extinction events, with the roots of their modem components appe aring in the region at that time, at least at the generic level. In contras t, distinctive asteroid species that are recognised from the Oligocene do n ot appear to have persisted into the later Cenozoic of the region. Incorpor ation of data from disarticulated elements commonly indicates that regular echinoids were at least as diverse as irregular echinoids. Some taxa that a re common in the Caribbean at the present day, such as diadematoids, that a pparently lacked a recognisable fossil record due to taphonomic factors, ar e recognised from throughout the Cenozoic on the basis of distinctive disar ticulated ossicles. (C) 2001 Elsevier Science B.V. All rights reserved.