摘要："Fossil turtles have been recovered from outcrops on the Río Purus, Río Acre, and Río Madre de Dios in the southwestern Amazon basin where the borders of Brazil, Peru, and Bolivia converge. The fossils are from two discernible horizons, both probably of late Miocene age and separated by the Ucayali Unconformity. The older horizon is the upper part of the Contamana Group, whereas the younger horizon is Unit A of the Madre de Dios Formation. The Contamana Group has yielded specimens identifiable as Stupendemys, a very large podocnemidid reported from Venezuela and Amazonia, and a new and unnamed taxon of podocnemidid represented only by the lower jaw. It is possible that the lower jaw belongs to Stupendemys, but the absence of any associated specimens prevents this assignment. The younger Madre de Dios horizon also yields Stupendemys, demonstrating that this large turtle lived both before and after the event that gave rise to the Ucayali Unconformity. A cervical attributable to a large species of Podocnemis was found in beds identified as either Unit A or upper Contamana Group"--P. [1].
