Search for: All records

Two silicified fossil woods are identified as a new species of Laurinoxylon from the Huitrera Formation at Laguna del Hunco in the Chubut Province of Argentina. Supporting characters include the absence of growth ring boundaries, vessels solitary or in short radial multiples, simple and scalariform perforation plates, alternate intervessel pitting, scalariform vessel-ray pits, scarce axial parenchyma, septate fibres, rays usually one to four cells wide, and idioblasts commonly associated with rays and rarely with the axial parenchyma. The fossil woods resemble members of the Perseae-Cinnamomeae-Laureae clade but do not closely match any extant genus; they therefore probably represent an extinct lineage. Although lauraceous woods are known from other Palaeocene and Eocene floras in Patagonia, the presence of the family at Laguna del Hunco was previously based only on leaf compressions without preserved cuticular details. Our new record confirms the occurrence of Lauraceae in the diverse Laguna del Hunco flora, which contains many genera associated with extant rainforest floras. 

Abstract Background and Aims Cunoniaceae are woody plants with a distribution that suggests a complex history of Gondwanan vicariance, long-distance dispersal, diversification and extinction. Only four out of ~27 genera in Cunoniaceae are native to South America today, but the discovery of extinct species from Argentine Patagonia is providing new information about the history of this family in South America. Methods We describe fossil flowers collected from early Danian (early Palaeocene, ~64 Mya) deposits of the Salamanca Formation. We compare them with similar flowers from extant and extinct species using published literature and herbarium specimens. We used simultaneous analysis of morphology and available chloroplast DNA sequences (trnL–F, rbcL, matK, trnH–psbA) to determine the probable relationship of these fossils to living Cunoniaceae and the co-occurring fossil species Lacinipetalum spectabilum. Key Results Cunoniantha bicarpellata gen. et sp. nov. is the second species of Cunoniaceae to be recognized among the flowers preserved in the Salamanca Formation. Cunoniantha flowers are pentamerous and complete, the anthers contain in situ pollen, and the gynoecium is bicarpellate and syncarpous with two free styles. Phylogenetic analysis indicates that Cunoniantha belongs to crown-group Cunoniaceae among the core Cunoniaceae clade, although it does not have obvious affinity with any tribe. Lacinipetalum spectabilum, also from the Salamanca Formation, belongs to the Cunoniaceae crown group as well, but close to tribe Schizomerieae. Conclusions Our findings highlight the importance of West Gondwana in the evolution of Cunoniaceae during the early Palaeogene. The co-occurrence of C. bicarpellata and L. spectabilum, belonging to different clades within Cunoniaceae, indicates that the diversification of crown-group Cunoniaceae was under way by 64 Mya.