Abstract

AGUIRRE-URRETA, M. Beatriz et al. Paleobiogeographic affinities of the Cretaceous invertebrates of the Neuquén Basin. Ameghiniana [online]. 2008, vol.45, n.3, pp.591-611. ISSN 1851-8044.

Paleobiogeographic affinities of Cretaceous marine invertebrates of the Neuquén Basin are analyzed based on a recent systematic revision. Two different marine intervals are considered. The first one corresponds to the Berriasian-Early Barremian when the basin was connected to the Pacific Ocean through a volcanic arc. The second is restricted to the Maastrichtian, when the basin was open to the Atlantic Ocean. During the first, the nautilids are monospecific showing Andean affinities. The ammonoids are represented by six families of tethyan affinities. Twenty genera and subgenera are replaced in time through immigration events, alternating between Andean and pandemic forms. The bivalve fauna has tethyan affinities, although a significant number of taxa are endemic. The decapods show similarities with others from England and Germany. The echinoids are represented by seven genera of different paleogeographic distribution, including endemic or Andean forms and others with a nearly cosmopolitan distribution. Maastrichtian mollusk faunas show affinities with the Weddellian Province. Near the K/P boundary and during the Danian the weddellian forms were replaced by warm-waters taxa from northern Brazil, the Caribbean and northern Africa. It is proposed that during the Early Cretaceous, paleotemperatures in the Neuquén Basin were similar to those in the Tethys, but probably not so high, whereas for the Maastrichtian, a global cooling would have caused the northern expansion of Weddellian forms. Finally, around the K/P boundary, a new global warming probably enhances the replacement of these faunas by other typical from low latitudes.

Keywords : Mollusks; Decapod crustaceans; Echinoids; Tethyan; Wedellian; Andean; Endemic.