CRETACEOUS EVIDENCE OF ASTERALEANLIKE POLLEN IN ANTARCTICA

BARREDA, V. D.; LUIS PALAZZESI; MARIA C. TELLERÍA; EDUARDO OLIVERO

Mendoza

Congreso; 4th International Palaeontological Congress; 2014

IPA- CONICET Mendoza

Asterales is an order of flowering plants that includes the highly diverse Asteraceae ?daisy family? along with ten other phylogenetically related families. Asterales appear to have originated in the Cretaceous, but no fossils from this period have been found to date to support this assumption regarding the origin of this group. Here we report new Asteralean-like fossil pollen grains from Antarctica that shed new light on the early evolution and diversification of Asterales. We recovered these specimens from Campanian/Maastrichtian sediments of the Santa Marta, Snow Hill Island and Lopez de Bertodano formations, on the James Ross and Vega islands, in Antarctica. We scored 75 binary pollen characters from 4 fossil forms and 55 extant species chosen to represent all families and tribes in Asterales. We conducted parsimony analyses to assess the phylogenetic position of each fossil using a highly supported molecular phylogenetic tree as backbone constraint. Our phylogenetic analysis places the new fossils within the early-diverging branches of Asteraceae and its sister Calyceraceae and Goodeniaceae. These fossils display some but not all the synapomorphies of the crown group, and hence leading us to infer that these fossils might represent members of the stem lineage. We reveal that some Asteralean lineages evolved in Antarctica during the Cretaceous, survived the K?P global extinction event, and radiated into the world?s highest latitudes of Gondwana by the Paleogene.