Image: Pachycephalosauridae head butting

Description: Hypothetical head-to-head interactions among pachycephalosaurids. (A) Bison-like head-shoving in large, broad-domed specimens such as Pachycephalosaurus wyomingensis; (B) Ovis-like clashing in Prenocephale prenes; (C) Capra-style broadside butting in high-domed and large-horned specimens such as subadult Pachycephalosaurus (“Stygimoloch” and “Dracorex”).
Title: Pachycephalosauridae head butting
Credit: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0068620
Author: Joseph E. Peterson, Collin Dischler, Nicholas R. Longrich
Permission: plos one
Usage Terms: Creative Commons Attribution 2.5
License: CC BY 2.5
License Link: https://creativecommons.org/licenses/by/2.5
Attribution Required?: Yes