A non-human dental piece was found in a Roman Empire tomb dated the 3rd century A.C. in Zaragoza (Spain). The morphology of this piece showed mixed brachyodont (carnivores) and hypsodont (herbivores) characteristics. As a result, the taxonomical assignation of the piece was impossible. Therefore, a protocol based on the DNA sequence of the cytochrome c oxidase subunit 1 mitochondrial region (COI) was applied. For this purpose, a pair of primers able to amplify this region in a large variety of animals was designed. The results point to a species of the Genus Bos (Family Bovidae). This assignation was later confirmed by these quencing of a short fragment of the mitochondrial D-loop region. A complete morphological description of the tooth is presented together with the DNA sequence study and comparison protocol.