Cretaceous bivalves from Ecuador and Northern Peru.
Résumé
New collections of bivalves from Cretaceous sections (Albian-Maastrichtian) in the central Andean Basin, a forearc basin in northern Peru/Ecuador, and the Paita Basins illustrate how paleobiogeographical affinities changed through geological time. During the middle Albian (at Chinimbini), the taxa are cosmopolitan. Upper Albian and Cenomanian faunas (Chinimbini, along Rio Misahualli in Ecuador, and at Pongo de Rentema in Peru) contain mainly Tethyan faunas (known from northern Africa, Texas, and southern Europe). The early Turonian faunas (mainly inoceramids) are Tethyan and have very wide extension. The Coniacian-Santonian faunas (Celendin Formation) are comparable to those from northwest and west Africa, but oysters have a somewhat younger age in Africa than in Ecuador and Peru. Most important, toward the Campanian-Maastrichtian, the faunas from the Paita Basins became largely endemic. For a few taxa of stratigraphical or systematic importance, a more detailed taxonomy is provided.