Luzia Antonioli

Atolchelys lepida, a new side-necked turtle from the Early Cretaceous of Brazil and the age of crown Pleurodira

We report a new pleurodiran turtle from the Barremian Morro do Chaves Formation, Sergipe-Alagoas Basin, Brazil. We tested the phylogenetic position of Atolchelys lepida gen. et sp. nov. by including it in a comprehensive cladistic analysis of pleurodires. The new species is a basal member of Bothremydidae and simultaneously the oldest unambiguous crown Pleurodira. The biogeographic and chronostratigraphic significance of the finding has implications for the calibration of molecular clocks studies by pushing back the minimum age of crown Pleurodira by more than 12 Ma (ca 125 Ma). The reanalysis of Pelomedusoides relationships provides evidence that the early evolution and relationships among the main lineages of side-necked turtles can be explained, at least partially, by a sequence of vicariance events.

Cenozoic distribution of Ephedripites Bolkhovitina (1953) ex Potonié (1958) emend. Krutzsch (1961) in Brazil

Abstract Here we present a critical revision of the occurrence of Ephedripites pollen grains during the Cenozoic of Brazil along with a new interpretation of the palaeo-biogeographical implications regarding the distribution of E. eocenipites, E. fusiformis, E. lusaticus and E. claricristatus (=E. tertiarius) in continental and marine sediments. Morphological features of these taxa, in general terms, differ from those of Cretaceous forms by the reduced number of plicae and thinner ribs. The revision of the Brazilian literature of Ephedripites point to a Paleocene distribution restricted to 30° S palaeo-latitude, whereas from the Eocene to the Pliocene, this genus is found in higher palaeo-latitudes of south-eastern and southern Brazil, attesting its occurrence in vegetation on dry or well drained soils.

Avaliação do potencial gerador de petróleo da seção Aptiana-Albiana da Bacia de Sergipe, integrando análises palinofaciológicas e dados de geoquímica orgânica

Data presented in this investigation refer to studies integrating palynofacies and organic geochemistry analyses that were performed on 51 samples of PEC-41-SE-9 well, located in the Sergipe Basin, Eastern Brazilian continental margin. It was evaluated the potential for oil generation, identifying the type and degree of maturation of the organic matter. Optical analyzes show that the organic matter is composed in greater proportion by amorphous organic matter in good preservation, with high fluorescence. It also presents a 67% average concerning the total composition of the kerogen. The phytoclasts usually are well preserved in almost all the section. The palynomorphs are composed of an association, predominantly, of spores and pollen grains of genus Classopollis, featuring a predominantly arid to semi-arid climate environment at deposition time. Presence of the dinoflagellate in the upper section displays the first marine ingressions that happened in the end of Aptian. Based on the qualitative and quantitative results of kerogen, it was possible to characterize three distinct palynofacies, in which the palynofacies I had the best features for quality and preservation of organic matter. The results show total organic carbon values up to 6.39% and Rock-Eval pyrolysis data pointed to the type II kerogen rich in organic matter suitable for the formation of hydrocarbon accumulations. The hydrogen index is found between 200 and 550 mg HC/g of total organic carbon, which shows good potential for oil and gas generation. Spore color index data conclude that the organic matter is found predominantly on the immature maturation phase, with SCI values of 4.0 to 4.5, corroborating with data of maximum temperature, of up to 432°C.