Fossil mollusk association from Isabela Island (Galápagos, Ecuador)

Abstract

In this paper a fossiliferous assemblage coming from Puerto Villamil (Isabela, Galápagos) is examined. The sandy sediments chiefly contain a molluscan association besides arthropod pincers, spicules of siliceous sponges, sea urchin spines, barnacle plates, rare foraminifers and abraded fragments of corals and briozoa. The mollusk assemblage represents a subtidal community associated with coral reefs and is dominated by Panamic forms. The modern aspect of this fauna and the radiometric ages till now proposed suggest a Pleistocene age for the Villamil deposits, although the presence of the extinct species Pegophysema spherica, for the first time reported from Isabela, might indicate a Pliocene age