The first Pliocene mammals from the northeast (Mesopotamia) of Argentina: its biostratigraphic and paleoenvironmental significance

CANDELA, ADRIANA MAGDALENA; NORIEGA, JORGE IGNACIO; REGUERO, MARCELO

JOURNAL OF VERTEBRATE PALEONTOLOGY

Society of Vertebrate Paleontology

Año: 2007 vol. 27 p. 476 - 483

0272-4634

The record of Neogene faunas from the northeast of Argentina (Mesopotamia) is saltuary; whereas, the late Miocene vertebrate-bearing horizons in this area contain a very abundant and diverse fauna, the Pliocene ones are poorly known and not fossiliferous until now. This situation makes the understanding of the biogeographic and evolutionary history of the Mesopotamian taxa difficult. In this contribution, we describe the first mammals recovered from the most basal levels of the Punta Gorda Group (= Alvear Formation) at Entre Ríos Province, assigned to the late Pliocene (Lower Matuyama) by previous paleomagnetic studies. These beds are paleomagnetically bracketed between 1.95-2.6 Ma (late Pliocene) in the Alvear section and help to refine the biostratigraphy of these species elsewhere in northeastern Argentina. The echimyids Paramyocastor diligens (Ameghino, 1888) and Eumysops sp., and the hegetotheriid Paedotherium cf. typicum herein reported support a Pliocene age for the sediments from which they were recovered. These mammals suggest a paleoenvironment characterized by semiarid and open lowlands, markedly different than that inferred for the Late Miocene in this area.