First fossil record of an Asteracean capitulum from Patagonia, Argentina

BARREDA, V; PALAZZESI, L; TELLERÍA, M.C.; KATINAS, L.; CRISCI, J.V.; PASSALIA, M.G.; CORSOLINI, R.; RODRÍGUEZ BRIZUELA, R.; BECHIS, F.

Budapest

Congreso; 8th European Palaeobotany Palynology Conference; 2010

Hungarian Natural History Museum

Morphological, molecular and biogeographical information bearing on early evolution of the sunflower alliance of families suggest that the clade containing the extant daisy family (Asteraceae) differentiated in South America during the Eocene, although paleontological studies on this continent have failed to reveal a conclusive support for this hypothesis. Here we present the first unequivocal fossil with head-like inflorescence and associated pollen grains from the Eocene of Patagonia, southern Argentina. It exhibits morphological features today recognized in taxa phylogenetically close to the root of the Asteracean tree, such as Mutisioideae and Carduoideae. This discovery provides the first strong paleobotanical support for the hypothesis of a South American origin of Asteraceae and an Eocene age of divergence. Moreover, this record joined with others from the Paleogene of Africa and Australia, would suggest that an ancestral stock of Asteraceae may have formed part of a Geoflora developed in southern Gondwana before the establishment of effective dispersal barriers within this landmass. This is the first capitulum of Asteraceae in the fossil record and perhaps the earliest indirect evidence for bird pollination in the family.