ARAUCARIAN FOSSIL RECORDS FROM SOUTH AMERICA AND WESTERN ANTARCTICA

EDGARDO . ROMERO, CAROLINA PANTI, MARIA DEL CARMEN ZAMALOA & SILVIA N. CESARI

Gramado, Brasil

Otro; XI Reunião de Paleobotânicos e Palinólogos; 2004

UFRGS e UNISINOS

The oldest undoubted macrofossil record of Araucariaceae in South America is represented by female and male cones, leaves and woods from the Jurassic Cerro Cuadrado petrified forest in Southern Patagonia. These include the unique known fossil representatives ofthe Bunya Section in this region. Similar age was reported for the fossil flora ofHope Bay (Antarctic Peninsula) that contains cone scales. During the Cretaceous, the family has the most northern records of South America in Colombia and Brazil, where cones and leaves were described respectively. Also, well-preserved cones and leaves were described from the Aptian of Patagonia. In the Antarctic Peninsula, cone scales were found in the Cerro Negro Formation (Aptian) and Alexander Island (Albian), whereas leaves were described from Late Cretaceous sediments in Vega Island and King George Island. Several of these Cretaceous records have been referred to the Eutaeta Section. During the Tertiary, Araucaria was present throughout Patagonia and the Antarctic Peninsula. Palynological records of Araucariacites australis share approximately the same geographic and stratigraphic distribution of the macrofossil remains. However, these pollen grains have the oldest record in the Upper Triassic of west central Argentina. Also, the species was widely recognised in the Jurassic and Cretaceous of north-western Patagonia, where macrofossils have not been still reported. The northernmost palynological findings in Argentina correspond to Miocene assemblages. Sporadic Cretaceous and Paleogene occurrences were documented in Brazil, Colombia, Peru and Guyana. All these data are analysed and discussed in order to reconstruct the history and paleoenvironmental conditions of the family in the region.