Anomocephalus and Tiarajudens (image) University of the Witwatersrand Share Print E-Mail Caption Head-butting and canine display during male-male combat first appeared some 270 million years ago. This is what researchers from the Evolutionary Studies Institute at Wits found when they conducted an updated and more in-depth study of the herbivorous mammalian ancestor, Tiarajudens eccentricus, discovered four years ago. Credit Wits University Usage Restrictions None Share Print E-Mail 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.