Various post-mortem processes can alter bone materials and then limit the use of their elemental or isotopic composition as markers for palaeo-environmental/climatic, paleodiet, or geochronological studies. Due to their complex and hierarchical structure, in vivo bones correspond to a highly heterogeneous tissue. The study of this heterogeneity, reinforced during fossilization processes, requires the use of adapted analytical techniques to investigate the variation of composition at microscale. Previous works have demonstrated that vibrational spectroscopic techniques like infrared micro-spectroscopy can be used to characterize the modification of composition induced by diagenetic processes and to determine the preservation state of the fossil samples. In this study, some spectral parameters, used to determine the composition of fossil bones, were measured by both infrared and Raman spectroscopy in order to compare the information supplied by these two techniques. Infrared and Raman micro-spectroscopy were then applied to fossil samples prepared as thin sections or polished thick sections. These first results of chemical mapping obtained on fossil bones by Raman micro-spectroscopy are in good agreement with the data obtained by FTIR micro-spectroscopy. These results demonstrated the capacity of this method for the understanding of diagenetic processes by monitoring the main components of fossil bone tissues (carbonates and collagen content, mineral crystallinity, etc.).