Middle Ordovician (Darriwilian) linguliform and craniiform brachiopods from the Precordillera (Cuyania Terrane) of West-Central Argentina

Abstract

Middle Ordovician lingulacean, trematid and a craniid brachiopods are described and illustrated for the first time from the uppermost part of San Juan Formation limestones of the Precordillera Basin, west-central Argentina. Sampled beds fall within the Ahtiella argentina brachiopod Zone, which according to associated conodonts is of early-mid Darriwilian age. The fauna consists of the linguloideans Glossella cuyanica n. sp. and Lingulasma? sp., the discinoidean Trematis sp., the siphonotretid Chilcatreta tubulata n. gen. et sp., and a conical shell which is referred provisorily to the order Craniida. The linguliforms from the Cuyania (Precordillera) terrane, though still poorly known, display close similarities to those inhabiting low to intermediate latitude palaeocontinents, particularly Laurentia and Baltica, in accordance with evidence from rhynchonelliform brachiopods.