Pachycephalosaurs (IMAGE) University of California - Berkeley Caption Dracorex (upper left) and Stygimoloch (upper right) are not distinct dome-headed dinosaurs, but young and nearly sexually mature, respectively, members of the species Pachycephalosaurus wyomingensis, according to a new study by paleontologists from UC Berkeley and the Museum of the Rockies Credit Holly Woodward/Montana State University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.