Nora Sabattini

LOWER PERMIAN POLYPLACOPHORA (MOLLUSCA) FROM ARGENTINA

Abstract Several polyplacophoran plates are preserved as external molds in the Lower Permian Rio Genoa Formation, Chubut Province, Argentina. These are the first reported Permian polyplacophorans from South America. The new genus and species Asketochiton chubutensis is described based on this material.

CISURALIAN CEPHALOPODS FROM PATAGONIA, ARGENTINA

Abstract Upper Paleozoic Cephalopoda of west-central Patagonia are revised, based on reexamination of all available specimens and of most localities in Chubut Province, Argentina. Nautiloidea Orthocerida are represented by Sueroceras irregulare Riccardi and Sabattini, S.? chubutense (Closs), Sueroceras sp., and Mooreoceras zalazarense Sabattini and Riccardi and Pseudorthoceratidae gen. and sp. indeterminate; Nautilida by Amosiceras reticulatum new genus and species; and Ammonoidea Goniatitida by Glaphyrites taboadai new species and Glaphyrites sp. This fauna belongs to the Cisuralian Sueroceras irregulare and Mooreoceras zalazarense assemblage zones.

UNA NUEVA ESPECIE DE RETISPIRA KNIGHT (GASTROPODA, BELLEROPHONTOIDEA) DEL PÉRMICO INFERIOR EN LA PROVINCIA DEL CHUBUT, ARGENTINA

Abstract. A NEW SPECIES OF RETISPIRA KNIGHT (GASTROPODA, BELLEROPHONTOIDEA) FROM THE LOWER PERMIAN OF CHUBUT PROVINCE, ARGENTINA. A new species of Retispira Knight (Gastropoda, Bellerophontoidea) from the lower Permian of the Tepuel-Genoa Basin, Chubut Province, Argentina, is described. The specimens come from the Cisuralian Euphemites chubutensis - Palaeoneilo aff. concentrica Zone. Retispira patagoniensis sp. nov. is a small, subglobose, phaneronphalus bellerophontid characterized by having a broad selenizone with fine lunulae and spiral lirae. Spiral and colabral elements generate a reticulate pattern. The new species developed in both shallow marine and deltaic facies and its distribution was mainly affected by water turbidity, depth and temperature. Its feeding habit may have been herbivorous, probably as an algal foliage dweller.