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 Paleobotany-Palynology Conference; 2010

Morphological, molecular and biogeographical information bearing on early evolution of the sunflower alliance of families suggest that the clade containing the extant sunflower family (Asteraceae) differentiated in South America during the Eocene, although paleontological studies on this continent has failed to reveal a conclusive support to this hypothesis. Here we present the first unequivocally fossil head-like inflorescence and associate pollen grains from the Eocene of Patagonia, southern Argentina,which exhibit morphological geatures today recognized in taxa phylogenetically close to the root of the Asteracean tree, such as Mutisioideae and Carduoideae. This discovery provides the first strog paleobotanicalsupport to the hypothesis of a south American origin of Asteraceaeand Eocene age of divergence. Moreaover, this record joined with othersfrom the Paleogene of Africa and Australia, would suggest that an ancestralstock of Asteraceae may have formed part of a Geoglora developed in southern Gondwanabefore the onset of continental fragmentation. This is the first capitulum of Asteraceaein the fossil record and perhaps the earliest indirect evidence of birdpollination in the family.