 In a research published in the International Journal of Osteoarchaeology by Timothy Vitales of the National Museum of the Philippines, it was described that at least five significant dog skeletons, three of which were complete, have been recorded in Santa Ana's protohistoric grave site.The dogs were dated to be between the 12th and 15th centuries AD.The research found that the dogs were buried on their own right, and were not companions for the dead.