New results in ancient Maya rituals researches: The study of human painted bones fragments from Calakmul archaeological site (Mexico)

•New insights into materials used in Maya culture for corpses preparation in burial practices.•Direct analyses on real human painted bones samples were performed.•The very first identification of the binders used to paint human skeletons in Maya burial ceremonies.•Obtained suggest the presence of an animal fat and natural gum compounds.•The multi analytical approach identified red pigments as Red Earth (or ochre) and Cinnabar.