ABSTRACT
Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 10(8)years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.
Subject(s)
Fishes , Fossils , Spectrometry, X-Ray Emission , X-Ray Diffraction , Animals , Brazil , Extinction, Biological , Fishes/anatomy & histology , Fossils/anatomy & histology , Spectrometry, X-Ray Emission/methods , Spectrophotometry, Infrared/methods , X-Ray Diffraction/methodsABSTRACT
In this work we study two types of wood fossils (Gymnosperms, Araucariaceae) from the Crato Formation of Araripe Basin in Brazil, from the Cretaceous Period. The samples were characterized by Raman and infrared spectroscopies, X-ray diffraction and scanning electron microscopy. The results obtained by different techniques showed that although the rocks surrounding the fossils have predominantly the same constitution - calcite - however, the formation processes of these types of wood fossils are quite different. One of the fossils, denominated as light wood, is predominantly composed of gypsum, while the other fossil, the dark wood, is rich in amorphous carbon, possibly the kerogen type. Implications relative to the environment where the plants lived millions years ago are also given. Finally, the results highlight the constitution of one of the most important paleontological sites of the Cretaceous Period in the South America.
Subject(s)
Fossils , Geological Phenomena , Wood/chemistry , Brazil , Optical Imaging , Spectrophotometry, Infrared , Spectrum Analysis, Raman , Time Factors , Wood/ultrastructure , X-Ray DiffractionABSTRACT
BACKGROUND: The aim of this work was to evaluate the interactions between aminoglycosides and the ethyl-acetate fraction of the fern Lygodium venustum SW (EAFLV) METHODS: The ethyl-acetate fraction was obtained from the ethanol extract of L. venustum and was assayed via the checkerboard method associated with aminoglycosides against two bacterial strains multiresistant to antibiotics. RESULTS: The antibiotic activity of all drugs, when associated with the ethyl-acetate fraction, was enhanced in an additive manner, except for the association between EAFLV and amikacin, which showed a synergistic interaction against the Escherichia coli strain. CONCLUSIONS: The results indicated that L. venustum can be a source of secondary metabolites to be used in association with antibiotics like aminoglycosides in antibiotic chemotherapy against resistant bacteria.
