CALMONIID TRILOBITES OF THE LOWER DEVONIAN SCAPHIOCOELLA ZONE IN THE ARGENTINE PRECORDILLERA

A trilobite faunule from the upper part of the Talacasto Formation at Cerro La Chilca, San Juan Province, Argentina, includes Calmoniidae th at are elsewhere known only from the Scaphiocoelia Assemblage Zone in Bolivia. Typical Scaphiocoelia Zone taxa at Cerro La Chilca are Tarija ctinoides jarcasensis SUAREZ SORUCO, 1971, Bainella cooperi nov. sp., closely allied to the Bolivian B. insolita (WOLFART, 1968), and Deltac ephalaspis sp. The most common calmoniid in the faunule is Bainella sa njuanina BALDIS, 1967, originally based on material from the Talacasto Formation at Fl Molle. Tarijactinoides jarcasensis is also reported f rom the Talacasto Formation at two additional localities in San Juan P rovince, one of which bears Calmonia nov. sp. A. The Scaphiocoelia Zon e, which includes the earliest record of diverse Devonian calmoniids i n Bolivia, had not previously been recognized outside Bolivia.