The Museo de La Plata houses numerous Miaolingian and Furongian fossils from the southern Precordillera of Mendoza, western Argentina, collected by Ángel V. Borrello during the 1960s. Early Miaolingian (Wuliuan) trilobites from these collections are described herein. The specimens studied come from allochthonous limestone blocks (San Isidro Olistoliths) of key fossiliferous localities of the San Isidro area (Cerro Martillo, Quebrada Oblicua, Quebrada Empozada, Quebrada San Isidro). Taxa comprise Athabaskia anax (Walcott), Glossopleura leona Lochman, Kootenia aff. K. incerta (Rusconi), Kootenia crassa Fritz, Oryctocephalites reynoldsi (Reed), Zacanthoides sp., Spencia? sp., Amecephalus normale? (Resser), Amecephalus laticaudum? (Resser), and Amecephalus sp. This assemblage is representative of the North American Glossopleura walcotti Zone, and closely allied to faunas from the Great Basin (Spence Shale), Sonora, and to a lesser extent from northwestern Idaho.