Early Pliocene gastropod diversity from the central eastern Pacific Ocean, Mexico (Guerrero) and their paleogeographical interpretation

Abstract

We report on an early Pliocene marine gastropod assemblage from Guerrero State, Mexico. Sixty-three gastropod species were identified and used to interpret their paleogeographic significance. From this assemblage, 15 species are reported as fossils for the first time, and 10 have not been previously reported older than early Pleistocene. The genus Conasprella is reported in the eastern Pacific for the first time. Bursa rugosa, Conus patricius, and Eupleura muriciformis are paciphile species, with a distribution on both sides of the Isthmus of Panama prior to the closure of the Central American Seaway, but distributed during the recent only in the Pacific. In addition, Architectonica nobilis and Distortio decussata were present in both the Atlantic and Pacific oceans during the Pliocene. These gastropods help to bridge a huge gap, between Nicaragua and southern California, USA, in fossil molluscan occurrences from the eastern Pacific part of the Tertiary Caribbean faunal province. They help document the early Pliocene Tertiary Caribbean faunal province in southern Mexico in the eastern Pacific before the final closure of the Isthmus of Panama during the late Pliocene.