Paleobiogeografía de la Región Mesopotámica
PALAEOBIOGEOGRAPHY OF THE MESOPOTAMIAN REGION. The geological characteristics of the Mesopotamian region of Argentina are described since the middle Tertiary. Miocene geological processes gave place to a marine transgression that floded Pampasia, separating the Andean margin from the BrazilianUruguayan region. The Pliocene regression allowed the development of fluvial plains with a diverse continental flora and fauna. During the Quaternary aridization and cooling of climatic conditions were alternate with warm to temperate and humid period of time. Finally in the Holocene, the whole region suffered again a marine transgression that leaved its records in the Lower Paraná River and Rio de la Plata estuarie.