Search for: All records

PremiseEocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genusAraucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to AustralasianAraucariaSect.Eutactausually are represented by isolated organs, making diagnosis difficult.Araucaria pichileufensisE.W. Berry, from the middle Eocene Río Pichileufú (RP) site in Argentine Patagonia, was originally placed in Sect.Eutactaand later reported from the early Eocene Laguna del Hunco (LH) locality. However, the relationship ofA. pichileufensisto Sect.Eutactaand the conspecificity of theAraucariamaterial among these Patagonian floras have not been tested using modern methods. MethodsWe review the type material ofA. pichileufensisalongside large (n= 192) new fossil collections ofAraucariafromLHandRP, including multi‐organ preservation of leafy branches, ovuliferous complexes, and pollen cones. We use a total evidence phylogenetic analysis to analyze relationships of the fossils to Sect.Eutacta. ResultsWe describeAraucaria huncoensissp. nov. fromLHand improve the whole‐plant concept forAraucaria pichileufensisfromRP. The two species respectively resolve in the crown and stem of Sect.Eutacta. ConclusionsOur results confirm the presence and indicate the survival of Sect.Eutactain South America during early Antarctic separation. The exceptionally complete fossils significantly predate several molecular age estimates for crownEutacta. The differentiation of twoAraucariaspecies demonstrates conifer turnover during climate change and initial South American isolation from the early to middle Eocene.