An updated comprehensive study of Cretaceous-Paleogene Angiosperms from Argentina

GANDOLFO, M. A.; M.C. ZAMALOA; ARCHANGELSKY ANA; ARCHANGELSKY SERGIO; VIVIANA BARREDA; CÚNEO RUBEN; ELIZABETH HERMSEN; ARI IGLESIAS; MAGDALENA LLORENS; MAURO G. PASSALIA; PEREZ LOINAZE

Edmonton

Congreso; Botanical Society of America Annual Meeting; 2015

Today, the angiosperms constitute the largest clade of seed plants with more than 300,000species distributed worldwide. They are found on every continent including Antarctica, inall types of terrestrial environments, and even in marine habitats. During the last decade,and with the advent of newer molecular sequencing techniques, major advances have madein elucidating the origin and evolution of the angiosperms; however, many aspects of theirevolutionary history still remain enigmatic. Paleobotanists have long recognized that theplant fossil record provides the only tangible evidence of the occurrence of angiospermsthrough time and contributes fundamental information that enlightens our understanding oftheir origin, life habits, history, radiation, and diversification. The majority of data on fossilangiosperms comes from the Northern Hemisphere because it has been intensively studied;the Southern Hemisphere?s paleofloras, in contrast, have been understudied and arerelatively poorly understood. Sedimentary rocks from Argentina, in southern South America, offer a wealth of angiosperm floras that provide critical data for addressing some of those questions. We are undertaking a comprehensive review of the micro- and macrofossil record of the angiosperms that inhabited Argentina from their first appearance during the late Barremian (earliest Early Cretaceous) to the Cretaceous-Paleogene (Maastrichtian-Danian) boundary, with the intent of understanding: 1-what taxonomic groups were present at what times and 2) the development of plant communities through time based on their constituent taxa. Data were gathered from 24 formations within six basins in Salta, Mendoza, and San Luis provinces, as well as in Patagonia. Results indicate that members of the basal angiosperms, Chloranthales, and monocots were already present during the Aptian-Albian in Argentina, and Clavatipollenites was represented by several species during the early Aptian; in the Cenomanian to the Campanian, the monocots, the eudicots (including members of the core eudicots) and the rosids (rosid I and II) became more diverse and similar to extant genera; and in the Paleocene, the asterids were members of the paleocommunities. Peninsullapolis gilli represents the oldest record of Proteaceae for Argentina and occurs in all the upper Campanian to Maastrichtian. Based on this review, it is evident that macrofossils are still poorly collected.