Late Miocene crocodylians from northeast Argentina: new approaches about the austral components of the Neogene South American crocodylian fauna

PAULA BONA; DOUGLAS RIFF; ZULMA BRANDONI DE GASPARINI

EARTH AND ENVIRONMENTAL SCIENCE TRANSACTIONS OF THE ROYAL SOCIETY OF EDINBURGH

ROYAL SOC EDINBURGH

Lugar: Edinburgo; Año: 2013 vol. 103 p. 1 - 20

1755-6910

The richest and more explored regions concerning Miocene crocodylians in SouthAmerica are the basins surrounding the areas of Urumaco (Venezuela), La Venta (Colombia), Acre(Northwest Brazil) and Parana´ (Northeast Argentina). Fossils from the late Miocene in the Parana´area were recovered from the ??Conglomerado Osı´fero?? (Ituzaingo´ Formation) and assigned to severaltaxa of Caimaninae (Alligatoroidea) and to a taxon of Gavialoidea. The late Miocene ??fauna?? ofcrocodylians recorded in northeast Argentina differs from coeval ones of northern South Americaby the absence of crocodyloids, some alligatorid genera (such as Purussaurus, Melanosuchus, andPaleosuchus) and by the scarce gavialoid species. Giant forms, conspicuous in the northern SouthAmerican deposits, are also absent in southern latitudes. Despite this, the austral South Americancrocodylian fauna exhibits strong affinities with the northern, contemporary forms, sharing taxa atgeneric (i.e. Caiman and Gryposuchus) and even specific levels (i.e. Mourasuchus nativus). The sharingof such freshwater taxa in the Miocene indicates partial connections of drainage basins throughswamp areas on their boundaries, and is evidence against the assumption of an intracontinentalcoeval seaway link in this continent proposed by several authors.