Some paleontologists are rewriting the history of the dinosaur. Experts have concluded that the Triceratops may have never existed, according to the Montana State University News Service and the Chicago Tribune. Since the 1800's, scientists have believed that the Triceratops and the Torosaurus were two separate dinosaurs, but now two researchers at Montana State University have concluded that the Triceratops and the Torosaurus were actually one in the same -- at different stages of growth. Both dinosaurs had a three-horned skull but while the Triceratops had a smaller frill, the Torosaurus had a larger frill with two large holes in it. MSU paleontologists John Scannella and Jack Horner noticed while considering more than 100 years of dinosaur research, that the remains of a young Torosaurus had never been found. After participating in a 10-year study led by Horner, researchers concluded that the Triceratops hadn't lived long enough to fully develop the frill that would identify them as a Torosaurus. Horner and Scannella published their findings in the July edition of the Journal of Vertebrate Paleontology. According to Scannella, the confusion over Triceratops and Torosaurus was easy to understand, because juvenile dinosaurs looked very different, and their skulls changed radically as they matured. "Paleontologists are at a disadvantage because we can't go out into the field and observe a living Triceratops grow up from a baby to an adult," Scannella said. "We have to put together the story based on fossils. In order to get the complete story, you need to have a large sample of fossils from many individuals representing different growth stages." Recent studies by scientists have revealed extreme changes in the skulls of pachycephalosaurs, tyrannosaurs and other dinosaurs that died out about 65 million years ago in North America. Scannella and Horner examined more than 50 Triceratops specimens for their study.