coexisted alongside additional pachycephalosaur species of the genera Sphaerotholus, as well as Dracorex and Stygimoloch, though these last two genera may represent juveniles of Pachycephalosaurus itself. Other dinosaurs that shared its time and place include Thescelosaurus, the hadrosaurid Edmontosaurus and a possible species of Parasaurolophus, ceratopsians like Triceratops, Torosaurus, Nedoceratops, Tatankaceratops, and Leptoceratops, the ankylosaurid Ankylosaurus, nodosaurids Denversaurus, and Edmontonia, and the theropods Acheroraptor, Dakotaraptor, Ornithomimus, Struthiomimus, Anzu, Leptorhynchos, Pectinodon, Paronychodon, Richardoestesia, and Tyrannosaurus. See also Timeline of pachycephalosaur research References External links Pachycephalosaurus in the Dinodictionary Pachycephalosaurus wyomingensis from National Geographic Online TEDx talk by Jack Horner on shape-shifting dinosaur skulls and dinosaur misclassification. Late Cretaceous dinosaurs of North America Pachycephalosaurs Taxa named by Erich Maren Schlaikjer Fossil taxa described in 1943 Taxa named by Barnum Brown Lance fauna Hell Creek fauna Paleontology in Montana Paleontology in South Dakota Paleontology in Wyoming Maastrichtian genus first appearances Maastrichtian genus extinctions Ornithischian genera