Environmental changes in Amazonia as evidenced by geological and paleontological data

Author(s)

Rossetti, Dilce de Fatima ^[1] ; de Toledo, Peter Mann ^[1]

Affiliation

^[1] Inst Nacl Pesquisas Espaciais INPE, BR-12245970 Sao Jose Dos Campos, SP - Brazil

• Document type: Review article
• Source: REVISTA BRASILEIRA DE ORNITOLOGIA; v. 15, n. 2, p. 175-188, JUN 2007.
• Web of Science Citations: 5

Abstract

Discussions focusing on the Amazon biodiversity might be significantly improved if a multidisciplinary approach is considered. In addition to biological influences. species divergence seems to be strongly motivated by stress in the physical environment. Therefore, the reconstruction of the geological history. provided by sedimentary and paleontological data, is crucial to provide different scenarios of paleolandscape evolution, and understand both their controlling mechanisms and the succession of the associated biota through geological times. For particular case of the Amazonia, these data are still scarce, spotty and dispersed in the literature, limiting the reconstruction of the mechanisms that might have influenced species evolution. In this paper. an overview concerning the sedimentary and paleontological records available for Amazonia is provided. Although rainforests seem to have been established in Amazonia since at least the Miocene, this compilation leads to defend the hypothesis that would be impossible to envision a stable environment with progressive species accumulation through time. Sedimentary and paleontological data support an Amazonian evolutionary theater that appears to be much more complex, being characterized by successive changes of the physical environment and of the associated biota as a result of oscillations in relative sea level, climate and tectonics. Although the impact of the first two factors has been highlighted in many publications, further information must be collected in order to fully characterize the importance of these changes over time. In particular, recent studies have increasingly demonstrated the great significance of tectonic reactivations in Amazonia as a major control on development of paleoenvironments through the Cenozoic. Tectonics seems to be acting even at the present, having a strong control on the establishment of drainage basins and on the distribution of flooded and terra firme areas. Therefore, this factor, not emphasized by previous biogeographic models, should be a point of a main concern for future studies focusing on the evolution and modern distribution of Amazonian species. (AU)