An Early Devonian, Eastern Americas Realm Faunule from the Coast of Southern Peru

Unconformably above Precambrian rocks near Cocachacra, Peru, is a limited exposure of conglomerate and siliceous lutite. In the latter are the brachiopods Acrospirifer cf. A. atlanticus (Clarke, 1907), Cupularostrum cf. C. macrocosta (Boucot, 1973), Atrypa sp. and a possible isorthid. Other fossils include a gastropod, a bivalve and fenestellid bryozoans. This limited fauna suggests tentative correlation to Emsian age beds of the Floresta Formation of Colombia. The brachiopods show an apparent Eastern Americas Realm affinity and are unlike any reported from Malvinokaffric localities of the same age near Lake Titicaca (175 km distant). The Cocachacra fossils indicate a warm marine paleoenvironment, as contrasted to the much colder Malvinokaffric Realm to the east. Occurrence of an Early Devonian faunule on the Peruvian coast southwest of Arequipa provides the first indication of Eastern Americas Realm faunas south of Colombia.