A review of paleogeographical and chronostratigraphical distribution of mesoeucrocodylian species from the upper Cretaceous beds from the Bauru (Brazil) and Neuque ´n (Argentina) groups, Southern South America Carlos Roberto A. Candeiro a, * , Agustı ´n G. Martinelli b a Museu de Minerais e Rochas, Instituto de Geografia, Universidade Federal de Uberla ˆndia, Av. Joa ˜o Naves de A ´ vila, 2160, Sta. Mo ˆnica, Uberla ˆndia, Minas Gerais, Brazil b Museo Argentino de Ciencias Naturales ‘‘B. Rivadavia’’, Av. A ´ ngel Gallardo 470, C1405DJR Buenos Aires, Argentina Received 1 October 2004; accepted 1 March 2006 Abstract This article offers a detailed overview of mesoeucrocodylian assemblages recovered from the Late Cretaceous southern South America Bauru and Neuque ´n groups as a result of extensive research during the past 110 years. The Bauru (Brazil) and Neuque ´n (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 Marı ´lia formations of Minas Gerais and Sa ˜o Paulo states, Brazil, and Candeleros and Bajo de la Carpa formations of Neuque ´n and Rı ´o Negro provinces, Argentina. Sixty formally described species of mesoeucrocody- lians 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 Neuque ´n 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 Argen- tina, 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. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Mesoeucrocodylia; Late Cretaceous; Bauru and Neuque ´n groups; Brazil and Argentina 1. Introduction The Bauru and Neuque ´n groups of Brazil and Argenti- na, respectively, contain some of the richest Upper Creta- ceous mesoeucrocodylian assemblages of Gondwana (see summary in Table 1, Fig. 1A and B). These groups are rel- atively well exposed in the Minas Gerais and Sa ˜o Paulo states of Brazil (e.g., Fernandes and Coimbra, 1996; Fer- nandes, 1998; Dias-Brito et al., 2001) and in the Neuque ´n, Rı ´o Negro, and Mendoza provinces of Argentina (e.g., Sti- panicic et al., 1968; Digregorio and Uliana, 1980; Leanza, 1999). Mesoeucrocodylian bones in the Bauru Group were first discovered in 1911 by Hermann von Ihering near the town of Sa ˜o Jose ´ do Rio Preto, Sa ˜o Paulo State, Brazil. In the middle of the twentieth century, Llewellyn Ivor Price pros- pected dinosaur-bearing deposits of the Marı ´lia Formation in the Tria ˆngulo Mineiro region, Minas Gerais State, Bra- zil, and provided many discoveries, including turtles, dino- saurs, and crocodyliforms (Price, 1945, 1950a,b, 1951, 1953, 1955). The studies in this region were interrupted 0895-9811/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsames.2006.08.001 * Corresponding author. Fax: +51 34 3214 2925. E-mail addresses: candeiro@yahoo.com.br, candeiro@ras.ufu.br (C.R.A. Candeiro), agustin_martinelli@yahoo.com.ar (A.G. Martinelli). www.elsevier.com/locate/jsames Journal of South American Earth Sciences 22 (2006) 116–129