Aratrocypris, an enigmatic new cyprid ostracod from the Tertiary of D.S.D.P. sites in the S.W. Pacific

Abstract. The new cyprid genus, Aratrocypris, based on four species ranging in age from Upper Palaeocene to Recent, is described. One species is left in open nomenclature and three, A.rectoporrecta (the type species), A.vaccamaris and A.praealta are described as new. The genus bears a unique plough-like structure anteroventrally and the possible function of this and the palaeoecology of the animal are discussed in detail. It is suggested that the plough-like structure, in association with other carapace structures such as the posterior position of the adductor muscle scars and the hinge, together with the strong degree of anterodorsal overlap, are indicators of a feeding mode associated with forward movement through the sediment. However, it is also possible that the animal was a filter feeder living within the sediment at a steep angle to the sea floor with the anteroventral structure protruded beyond the sediment water interface.