Paleoecology and paleoenvironments of Podocarp trees in the Ameghino Petrified Forest (Danian), Patagonia, Argentina

BREA, M., MATHEOS, S.D., RAIGEMBORN, M.S., IGLESIAS, A., ZUCOL, A.F. AND M. PRÁMPARO

GEOLOGICA ACTA

UNIV BARCELONA

Lugar: Barcelona; Año: 2009

1695-6133

Central Patagonia during the Early Paleocene (Danian) was warm-temperate and dominated by evergreen coniferous forests. Abundant permineralized conifer woods and some dicot and palm compression leaves were found in Ameghino Petrified Forest and are evidence of this type flora. All the permineralized woods and large trunks found are assigned to the species Podocarpoxylon mazzonii. An estimated tree height of 17 – 29 m was calculated on the basis of diameter measures. Based on 14 series and 169 rings, the mean ring width and Mean Sensitivity (MS) were 1.23 mm and 0.19 respectively. The growth rings are moderately wide, extremely uniform and complacent, indicating that the environment was favourable and constant without stress limiting for tree growth. Following the coniferous quantitative analysis outlined by Falcon-Lang, Podocarpoxylon mazzonii growth ring anatomy suggests that these trees have been an evergreen habit. Fossil flora, growth ring and sedimentological analyses suggest that this mostly evergreen coniferous forest developed under warm-temperate conditions without limiting factors.