Redescription of Pleurotomaria gerthi Weaver, 1931 (Gastropoda, Vetigastropoda), from the Early Cretaceous of Argentina: New Data on Its Age, Associated Palaeoenvironments and Palaeobiogeographic Affinities

Abstract Pleurotomaria gerthi Weaver, 1931 (Gastropoda, Vetigastropoda) from the Pilmatue Member of the Agrio Formation is redescribed and reillustrated on the basis of 38 newly collected specimens from nine localities in Neuquen Province, Argentina, including its type locality. The holotype housed in the C.E. Weaver collection is also refigured. Pleurotomaria gerthi-bearing levels, dated using a detailed ammonoid zonation, are late Valanginian—early Hauterivian. Taphonomic and sedimentological data gathered at three of the nine studied sections indicate that P. gerthi dwelled in shallow marine settings above the storm-weather wave-base. Associated palaeoenvironments are interpreted as inner shelf and inner carbonate ramp settings deposited under the influence storm currents and waves. The species lived on well-oxygenated soft sandy and patchy bioclastic substrates in normal marine warm-temperate waters within the photic zone, associated with a high-diversity macrofossil assemblage. Our study shows that i...