Evolution of the southeastern Brazilian reptile fauna from Cretaceous: paleontology, phylogeny and biogeography

Abstract

This project's main objective is the study of phylogenetic and biogeographic patterns of the reptile fauna of southeastern Brazil, From the upper Cretaceous to the present time, allowing the characterization of expansion and retraction pulses that took place in the past 70 million years, and responsible for the present configuration of the reptile biodiversity. The improvement of knowledge about these processes will help in the recognition of parameters leading to the loss of biodiversity (in different temporal scales) in southeastern Brazil and ultimately contribute to the establishment of conservation strategies and sustainable use of natural resources. Thus, and for the first time within the Biota Program of FAPESP, we intend to include paleontological data in the study of biodiversity. The traditional definition of extant reptiles encompasses the clades Quelonii, Crocodylia and Squamata (including snakes, lizards and amphisbaenians). These groups are represented in the Cretaceous and Tertiary fossil record of Brazil, thus providing an ideal database to the approach adopted in this project. Southeastern Brazil includes the states of São Paulo, Rio de Janeiro, Espírito Santo and Minas Gerais, a privileged study area in the sense that it harbors a significant fraction of the Atlantic Forest and Cerrado biomes, besides the Bauru, ltaboraí and Taubaté fossil basins, and the carstic region of the Ribeira river valley. This assemblage of sedimentary basins, biomes and carstic caves offers a unique opportunity for sampling reptiles in a timeframe of 70 million years. ln order to develop the study here proposed, it is necessary improve and organize our knowledge of the reptile diversity through geological time. The confection of such a survey will allow the cross-checking of data of extant and past faunas in a vertical axis (chronostratigraphic axis) hitherto unexplored within the Biota Program. The implementation strategy possesses seven major tines of scientific activities: 1) the survey of the reptile diversity in the state of São Paulo from the upper Cretaceous to Recent, thus compiling a database including all recent species described so far as well as the specimens in natural history collections. 2) To collect living and fossil reptiles in the biomes and fossil basins of southeastern Brazil. 3) To develop phylogenetic studies of key extant and extinct taxa. 4) ln the case of extant key taxa, to elaborate molecular and morphological phylogenies in order to contrast their results. 5) To combine data on the distribution of fossil and living taxa with phylogenies and identified timeframes, to study past and present biogeographic and faunistic patterns of the Brazilian southeast. 6) To develop fine morphological studies aiming the understanding of the evolution of complex structures in reptiles. 7) To strength collections and study groups of vertebrate paleontology in the state of São Paulo through the creation of laboratories for preparation and study of fossils in the Museu de Zoologia and the FFCLRP of the Universidade de São Paulo. The Cretaceous and Tertiary will be surveyed in the following basins: 1) Bauru basin (upper Cretaceous); 2) ltaboraí basin (paleocene); Taubaté basin (Eocene -Oligocene). Pleistocene and Holocene material will be collected in the carstic caves of the Vale do Ribeira (Ribeira river valley) in the state of São Paulo, in southern Bahia and northern Minas Gerais. The extant reptile fauna will be sampled in localities within the two major biomes of the southeast: the Atlantic Forest and the Cerrado. Other regions of Brazil will be surveyed in order to provide a comparative background for the reptile diversity pattern found in the Brazilian southeast. (AU)