The oldest-known horned dinosaur is the Zuniceratops christopheri. The fossil remains of this animal were recently discovered by Chris Wolfe, an eight-year-old third-grader from Phoenix, Arizona. This dinosaur lived some 90 to 92 million years ago, had three horns, and might have been 10 to 12 feet (3 to 4 meters) long, with a weight of approximately 200 to 250 pounds (100 to 150 kilograms). The remains were discovered in western New Mexico and include jaw parts, the brain case, teeth, a horn, and the brow.