A new record of Amosiceras reticulatum Sabattini et al. (Cephalopoda, Nautilida) from the Upper Paleozoic Tepuel-Genoa Basin, Chubut Province, Argentina

PINILLA, KARINA; PAGANI, M.A.

Mendoza

Congreso; 4th International Paleontological Congress; 2014

Cephalopods from the Neopaleozoic Tepuel-Genoa Basin in Chubut Province, Argentina, are relatively rare and endemic; however, some species have proved to be useful for biostratigraphy. Two successive cephalopod biostratigraphic units were proposed in the basin, the Sueroceras irregulare and Mooreoceras zalazarensis zones, which were referred to the early Permian on the basis of the occurrence of diagnostic mollusks. The M. zalazarensis Zone is mainly characterized by the eponymous species, as well as Glabrocingulum (Stenozone) Batten, Eirlysia Batten (Gastropoda), Atomodesma von Beyrich, Merismopteria Etheridge, Netschajevia Likharev (Bivalvia) and Castelvenus Yancey (Scaphopoda). A new record of the nautilid Amosiceras reticulatum Sabattini et al., a taxon previously described from Piedra Shotel and El Molle localities, is presented herein. The material studied comes from the Río Genoa Formation at Salar de Ferraroti, from levels assigned to the Mooreoceras zalazarensis Zone. The associated faunas include the gastropods Retispira patagoniensis Pinilla and Sabattini, Borestus lunatus Pinilla et al., Glabrocingulum (Glabrocingulum) poperimensis (Maxwell), Euphemites chubutensis Sabattini, Sinuitina (Spirilira) gonzalezi Sabattini, S. (Spirilira) tenuis Pinilla et al., Eirlysia sp., Amaurotoma sp, Mourlonia cuneoi Ferrari and Sabattini, Austroneilsonia sp., Euomphalus sp. and Glabrocingulum (Stenozone) argentinus (Reed), which suggest a KasimovianArtinskian age. Since Amosiceras reticulatum mostly resembles Knightoceraspustulum Unklesbay and K. oxylobatum Miller and Downs, from the early Pennsylvanian(Bashkirian) of North America, the age range of the Mooreoceras zalazarensis Zone should be reconsidered.