Echinoderms of the Mid-Cainozoic White Limestone Group of Jamaica

Echinoids are locally common in certain units of the White Limestone Group, Jamaica. The upper Middle to Upper Eocene Troy Formation (lagoonal palaeoenvironment) includes common clypeasteroids, particularly neolaganids. In contrast, the dominant echinoids of the coeval Swanswick Formation (shelf edge setting) are oligopygoids and spatangoids. In deeper water, an upper Middle Eocene horizon low in the Montpelier Formation includes clypeasteroids and cidaroid spines, although these may have been derived by downslope transport. Nominal echinoid taxa are almost unknown from the Upper Eocene and Lower Oligocene of the island. The Oligocene Lepidocyclina-dominated biofacies of the Moneague Formation (shelf edge) includes a fauna in which the spatangoids are reminiscent of similar Middle Eocene settings, although not as diverse, but the oligopygoids are replaced by Clypeaster spp. The shallow-water Miocene Amphisorites matleyi-yielding limestones of the Moneague Formation has yielded few echinoid remains apart from clypeasteroids, particularly Clypeaster spp., but a reef fauna preserved in deeper-water chalks (Montpelier Formation) after downslope transport retained a greater diversity of species. Faunas of the Oligocene and Miocene units have a distinct modem aspect. However, the well-lithified limestones of the White Limestone Group do not favour collecting techniques that would enable accurate determinations of diversity of echinoderms.