The past preparation processes carried out on the holotype of the species Sinohippus sampelayoi (Villalta and Crusafont, 1945) (Equidae, Anchitheriinae) have been analyzed. This singular piece, a right hemimandible housed in the Museo Geominero since 1940’s decade, has undergone an unusual number of treatments such as adhesion, consolidation or even partial removing of bone to expose unerupted teeth. The different procedures have been identified and are presented in this paper in a chronological succession. Besides, some materials as mortars, which have been historically employed to preserve or to cast this fossil, have been analyzed using X-ray diffraction. Due to the importance of this fossil, a high quality copy has been made based on the patent Nº ES 2 273 577 A1 (Nº 200.501.432), which combines the use of different materials in the same replica thus obtaining more realistic results.