Abstract

The Las Chinas-Cerro Guido Complex is located north of the Magallanes Region, southern Chile, and has been visited by scientiic expeditions since 1898. Summarizing the results of this previous works, a Late Cretaceous environment (Campanian-Maastrichtian) was reported with a transition of marine to deltaic deposition. The paleolora was dominated by Sterculia, without Nothofagus, and the fauna restricted to curculionid insects. As a result of a recent multidisciplinary work, including detailed stratigraphy, satellite analysis, palynology, invertebrate and vertebrate paleozoology, palaeobotany and petrology, the existence of a river delta was established, controlled by tides and three stages of plant assemblages. The upper level contained Nothofagus leaf imprints, underlying partially-articulated hadrosaur and other undetermined vertebrate remains. The presence of Nothofagus, key genus of the sub Antarctic forests of Chile and Argentina, can be interpreted as strong evidence of Antarctic-Patagonian land bridges during the latest Cretaceous, presence that could be correlated to an overall decline in sea level and a brief cooling event following the Cretaceous greenhouse period. Indeed, this Nothofagus record is the oldest in America, and the dinosaurs indings are the southernmost worldwide excluding Antarctica.