Morphology and cuticular analysis of the Cretaceous Paleoflora from the Springhill Formation, Southern Patagonia, Argentina

CARRIZO MARTIN A.; DEL FUEYO GEORGINA M.

Mendoza

Congreso; 4th International Palaeontological Congress. The history of life: a view from the Southern Hemisphere; 2014

CCT MENDOZA & IPA

MORPHOLOGY AND CUTICULAR ANALYSIS OF THE CRETACEOUS PALEOFLORA FROM THE SPRINGHILL FORMATION, SOUTHERN PATAGONIA, ARGENTINA Martín A. Carrizo1 and Georgina M. Del Fueyo1 1: Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". - MACN. Av. Angel Gallardo 470, 1405 Buenos Aires, Argentina. blackdisk@gmail.com The Springhill Formation (Early Cretaceous) stands out within the Austral Basin (Argentina) due to its economical value as an oil producer unit and its geographical extension, but it is currently lacking detailed megafloristic studies, the few existing ones being based on fragmentary plant materials. A thorough survey of the outcrops of the Springhill Formation was carried out in both geological and paleobotanical aspects, including both banks of the Pueyrredón and Posadas Lakes, the eastern bank of the Salitroso Lake, the northern bank of the Ghío Lake, southern part of the Buenos Aires Lake and the proximities of Estancia El Salitral located in Santa Cruz Province, Argentina. Stratigraphic sections were measured at Estancia El Salitral and Río Correntoso localities, in which abundant fossil plant material was collected, consisting mainly in compressions of leafy shoots with several branching orders, complete to partially preserved fronds, simple to pinnate leaves and fertile scales. The analysis of these materials allowed the description of 21 new taxa which add to the already known flora of the Springhill Formation; 9 of these taxa were found in Estancia El Salitral, and 12 in Río Correntoso. The floristic diversity of the unit has increased through the discovery of the first megafossils of pteridosperms (Ruflorinia sp. nov. 1 and Ruflorinia sp. nov. 2) and ginkgophytes (Baiera sp. 1 y Baiera? sp. 2), while new taxa has been described within the divisions Pteridophyta, Cycadophyta and Pinophyta. Analyses of the epidermis of vegetative and reproductive structures of the various groups included within this megaflora have proved to be a valuable tool for the recognition and individualization of species, and have suggested a wet to temperate climate during the deposition of the Springhill Formation at the studied localities. Also, the compositional comparisons among coetaneous flora from the Western Gondwana have shown that the plant community from the Springhill Formation is more similar to the well known Baqueró Flora than those one from the Kachaike, Antarctica or Crato formations. Sponsored by ANPCyT PICT 2012/528, CONICET PIP 112-201201-00212.