MAASTRICHTIOCARIS ROSTRATUS NEW GENUS AND SPECIES, THE FIRST CRETACEOUS CYCLOID

Abstract

Since the description of the first cycloid from the Carboniferous of Yorkshire, England (Phillips, 1835) the Cycloidea have been placed in many different groups within the Arthropoda. These include agnostid trilobites (Phillips, 1835), xiphosure merostomes (Packard, 1872; Oosterink, 1978), limuloid-like crustaceans (Woodward, 1905), decapod brachyurans (Trauth, 1918), branchiurans (Hopwood, 1925), copepods (Clark, 1989), and maxillopodan crustaceans (Schram et al., 1997). Glaessner (1928) considered that the Cycloidea might be derived from the Paleozoic Phyllocarida. More recently Vannier and Babin (1995) postulated the enigmatic arthropod, Hanadirella known from the Ordovician of Saudi Arabia and France, as a possible ancestor of the cycloids. However, cladistic analysis (Schram et al., 1997) indicates that the Cycloidea possibly belong within the Crustacea as a sister group of the Copepoda. The Cycloidea were, heretofore, known from beds extending from the early Carboniferous until the late Triassic. They are found in Austria, Belgium, Bosnia, Central Asia, France, Germany, Ireland, Italy, Russia, Netherland, the U.K. and the U.S.A. (Glaessner, 1969; Schram et al., 1997). One of the youngest cycloids previously known, Halicyne cf. H. agnota von Meyer, 1847, was reported from the Muschelkalk of Winterswijk, in Netherland (Oosterink, 1978; 1986). However, in the course of the ongoing investigations of the Maastricht Formation in the Maastrichtian type area, southern Limburg, Netherland, three specimens of what clearly seem to be cycloids have come to light. The distinctive anatomy of these fossils, all from the Meerssen Member (IVf4) of the ENCI quarry, require erection of a new genus and species. ### Class MaxillopodaDahl, 1956 Order Cycloidea Glaessner, 1928 Family Cyclidae Packard, 1885 Genus Maastrichtiocaris new genus #### Diagnosis Carapace oval; with relatively broad, flat …