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In this paper we performed the study of two coprolites (fossilized feces) collected from the exposed levels of the Pedra de Fogo Formation, Parnaiba Sedimentary Basin, and Rio do Rasto Formation, Paraná Sedimentary Basin, both of the Palaeozoic era (Permian age). They were characterized using X-ray diffractometry, infrared, Raman and energy dispersive spectroscopy techniques in order to aid our understanding of the processes of fossilization and to discuss issues related to the feeding habits of the animals which generated those coprolites, probably cartilaginous fishes. The results obtained using a multitechnique approach showed that although these coprolites are from different geological formations, 3000 km away from each other, they show the same major crystalline phases and elemental composition. The main phases found were hydroxyapatite, silica, calcite and hematite, which lead to infer that those coprolites were formed under similar conditions and produced by a similar group of carnivore or omnivore fishes. [ABSTRACT FROM AUTHOR]

The Jandaíra Formation, Potiguar Basin, is well known for hosting a rich marine fauna from the Late Cretaceous of Brazil. Among the organisms that compose this diverse fossiliferous assemblage, the gastropods stand out for their abundance of individuals. In this study, four samples of Tylostoma sp (LP/UFC CRT 2868, LP/UFC CRT 2869, LP/UFC CRT 2870 and LP/UFC CRT 2871) were analyzed in order to understand the different diagenetic processes involved in their preservation. The fossil specimens were collected near Mossoró, state of Rio Grande do Norte. In this work, we have combined a set of high-resolution techniques such as Raman spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Scanning Electron Microscopy (SEM) and energy dispersive spectroscopy (EDS) to characterize the fossil specimens mineralogically. All fossil shells are preserved as internal molds, meaning they have lost their original organic matter. After the decomposition of organic debris, the inner part of the shell is filled with surrounding sediment. Our results revealed dolomite as the dominant phase in host rock. On the contrary, the fossil samples LP/UFC CRT 2868, LP/UFC CRT 2869, LP/UFC CRT 2870 and LP/UFC CRT 2871 showed calcite as the dominant phase. These data indicate that a similar diagenetic process was involved in the preservation of these fossil shells. Here, we document discoveries and new perspectives for looking at the abundance of fossil shells in the Jandaíra Formation. [Display omitted] • We carried out quantitative/qualitative analyses in different fossil shells from Jandaíra Formation. • The fossil shells are preserved by calcium carbonate, where calcite is the main phase. • This data reveals that all fossil shells share a unique preservation pathway in Jandaíra Formation. [ABSTRACT FROM AUTHOR]