COULONIA PLATYSPINA N-SP, A NEW ASTROPECTINID SEA STAR FROM THE LOWERCRETACEOUS OF MOROCCO

The asteroid Coulonia platyspina n.sp. from the Lower Cretaceous (Barr emian) of the Tamanar coast, north of Agadir, Morocco, belongs to a ge nus hitherto known only from the Hauterivian of Switzerland. The ventr al surface of the three specimens as well as remains of irregular echi noids are exposed on the lower surface of a fine-grained sandstone bed ; presence of tool marks on this surface indicates that the animals we re dragged along the bottom during a tempestite event before final bur ial. Very broad inferomarginals with deep fasciolar channels and colum nar true paxillae suggest the capability for self-burial comparable to that found in living Astropecten and Luidia. These morphological feat ures are not known from Jurassic astropectinids, although numerous fos sils from rocks of this system have been described. Based on stratigra phic position, fasciolar development appears to represent the phylogen etically derived state and suggests a broadening of astropectinid ecol ogical capabilities during the later Mesozoic, possibly under the stim ulus of the Mesozoic increase in predation pressure documented for oth er groups. Timing discussed here indicates studies of asteroid phyloge ny need to encompass apparently more primitive members of the Paxillos ida than the fasciole-bearing genera Astropecten and Luidia, the typic al paxillosidan examples of such studies.