Middle Ordovician linguliformean microbrachiopods from western Argentina: new data and biogeographic implications

Abstract

New linguliform microbrachiopods from the Middle Ordovician are described and illustrated. This fauna was recovered from the uppermost beds of the San Juan Formation in two sections of the Central Precordillera (Argentina), which are accurately dated to the Lenodus pseudoplanus Zone (middle Darriwilian). The fauna consists of the obolid Luthieria diminuta n. gen. n. sp., and the acrotretids Eoconulus tucunucoensis n. sp., Conotreta andina Lavié, Serra, and Feltes, Scaphelasma zharykensis Popov, and Numericoma rowelli Holmer et al. This low-diversity lingulate association displays close similarities with coeval faunas that inhabited the Laurentia, Baltica, and Kazakhstanian regions, in agreement with evidence from other linguliform and rhynchonelliform brachiopods.