A review of paleogeographical and chronostratigraphical distribution of mesoeucrocodylian species from the upper Cretaceous beds from the Bauru (Brazil) and Neuquen (Argentina) groups, Southern South America

This article offers a detailed overview of mesoeucrocodylian assemblages recovered from the Late Cretaceous southern South America Bauru and Neuquen groups as a result of extensive research during the past 110 years. The Banru (Brazil) and Neuquen (Argentina) groups yield numerous mesoeucrocodylian remains, mainly of Turonian-late Maastrichtian (Late Cretaceous) age. The majority of the discoveries were made in the Adamantina and Marilia formations of Minas Gerais and Sao Paulo states, Brazil, and Candeleros and Bajo de la Carpa formations of Neuquen and Rio Negro provinces, Argentina. Sixty formally described species of mesoeucrocodylians are recognized on the basis of disarticulated materials; among them, notosuchians, sebecosuchians, and peirosaurids are the best represented. At least one species is common to the Bauru and Neuquen groups, and close phylogenetic affinities are postulated for the remaining taxa. The fossil record of these two South American units shows three main peaks of diversity: in the Cenomanian of Argentina, the Santonian of Argentina and Brazil, and the Maastrichtian of Brazil. The absence of notosuchians and sebecosuchians in the late Campanian-Maastrichtian of Patagonia is coincident with the paleoenvironmental changes in that landmass by that time, as well as with the increase in diversity of several groups of theropod dinosaurs. In contrast, highly specialized carnivorous mesoeucrocodylians are abundant in the Maastrichtian of the Bauru group of Brazil, whereas other tetrapod carnivorous groups are scarcely represented. (c) 2006 Elsevier Ltd. All rights reserved.