Controlled chemical cleaning in paleontological preparation: the use of gels on vertebrate fossil remains from the Late Cretaceous of Spain

The conservation of paleontological heritage depends greatly on the diversity and complexity of the materials that compose both the fossils and the matrix that includes and flls them. A common practice in fossil preparation treatments consists in removing part of the surrounding matrix that, in some cases, prevents direct access to the specimens or puts its conservation at risk. For this reasons, it is necessary the use of reliable treatments that do not compromise the fossil stability during the process. Cleaning methods based on the use of gelifed solutions can be a remedy for some of those treatments in which the use of traditional techniques put in danger the preservation of the fossils. Here it is discussed the efcacy of diferent chemi‑ cal cleaning techniques with gelled solutions using diferent thickening agents, acids, chelants and surfactants that can be applied to the fossils from Lo Hueco fossil site (Cuenca, Spain).