MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
Fossil pollen indicates an explosive radiation of basal Asteracean lineages and allied families during Oligocene and Miocene times in the Southern Hemisphere
BARREDA, V.; PALAZZESI, L.; TELLERÍA, M.C.; KATINAS, L.; CRISCI, J.V.
REVIEW OF PALAEOBOTANY AND PALYNOLOGY
ELSEVIER SCIENCE BV
Año: 2010 vol. 160 p. 102 - 102
Much of our knowledge of the past distribution and radiation of Asteraceae and allied families depends on thefossil pollen record. In recent years, new discoveries are coming to light from southern Africa, Australia, NewZealand, and southern South America (Patagonia). Unequivocally assigned morphotaxa from accurately datedsediments havepermitted for the first time a comprehensive reviewof the past distribution of themost importantcore of the sunflower alliance of families (Menyanthaceae, Goodeniaceae, Calyceraceae and Asteraceae). Themain goal of this contribution is to explore the major evolutionary radiation of the basal lineages of Asteraceae(Mutisioideae and Barnadesioideae) and allied relatives (Menyanthaceae, Goodeniaceae and Calyceraceae) onthe basis of the worldwide fossil pollen records. Several taxa, which today are restricted to isolated geographicregions, were widespread in the Southern Hemisphere during Paleogene times. Menyanthaceae, Goodeniaceaeand Mutisioideae (Asteraceae), for example, had a wide distribution over Gondwanan landmasses in theOligocene and are now drastically reduced in their geographic range. Early Neogene records, in contrast, suggestextinction and diversification events that progressively led to the present day configuration. In broad terms, thedistribution of Miocene fossils assigned to this clade (Barnadesioideae, Nassauvieae, and Calyceraceae) agreeswith that of their present distribution. The major floristic turnovers coincided with the final isolation ofAntarctica, leading to cooler, drier, and more seasonal climates and forced the evolution and distribution of theseGondwanan elements.