The micro-and megafossil record of Nothofagaceae from South America

Abstract

We compiled the numerous fossil records (486) assigned to Nothofagaceae including pollen grains (from surface sediments and continental and oceanic borehole cores), leaves, woods and reproductive structures from South America. All the records are revised and the latest systematic treatments and ages of the bearing strata of each record are followed. When possible, we proposed a subgeneric affinity to each record based on updated bibliography. Fossils of three (Nothofagus, Fuscospora and Lophozonia) of the four subgenera are found in similar proportions through time since the Late Cretaceous. Fossils with reliable affinity with subgenus Brassospora were not found in South America. Most of the records are concentrated in the southern tip of South America (Patagonia Region) and nearby areas. After a significant presence of Nothofagaceae in the Cretaceous, the family declined in diversity and abundance in the Palaeocene and then increased from the Eocene to the Miocene. In the Miocene, the records reach their maximum diversity and abundance, and Nothofagaceae usually dominate the assemblages of pollen, leaves and woods from Patagonia. Pliocene Nothofagaceae records are virtually absent, probably because sedimentary rocks of that age are rare in Patagonia. The fossil record for Nothofagaceae varies according to environmental turnover; when tropical/subtropical floras were present in Patagonia in the Palaeocene-early Eocene, Nothofagaceae contracted southwards and when open steppes developed in the Miocene of east Patagonia, Nothofagaceae contracted westward.