The remains of the oldest known domesticated dog in North America have been discovered in a sample of fossilized human waste. The canine bone fragment is 9,400 years old, or 65,000 in dog years. The discovery suggests that prehistoric man treated and cared for his faithful Fido but found that he was more fulfilling as food. University of Maine researcher Samuel Belknap was studying the diet of prehistoric man when he came upon the dog skull fragment in a cave in southwest Texas. The bone is tinted orange, meaning it passed through a human digestive tract. Older dog remains have been found in Europe, but this sample is the oldest in the Americas.