Scientists have uncovered evidence of head butting and other male-to-male physical combat behaviors in herbivorous mammalian ancestors that walked the Earth 270 million years ago.
Tiarajudens eccentricus boasts protruding saber-tooth canines and occluding postcanine teeth, which is puzzling because it was a vegetarian, the University of Witwatersrand reported. The discovery of the Brazilian species allowed for the reanalysis of the South African species Anomocephalus africanus, which was uncovered a decade ago. Both species have similar features, but the South African species did not have saber-toothed fangs.
Large canines are used for fighting between males in today's deer, and these findings suggests T. eccentricus put them to a similar use. The study provides the earliest evidence of male herbivores using their teeth to fight.
"It is incredible to think that features found in deer such as the water deer, musk deer and muntjacs today were already represented 270 million years ago," said Juan Carlos Cisneros from the Evolutionary Studies Institute at the University of the Witwatersrand.
Tiarajudens' marginal teeth proved to be located in a bone from the palate called epipterygoid.
"This is an extraordinary condition as no other animal in the lineage leading to mammals show marginal dentition in a bone from the palate," said researcher Fernando Abdala.
A group of mammal fossil relatives called dinocephalians had bones in their foreheads that were significantly thickened. This trait suggests the ancient animals may have participated in head-butting behaviors, which can also be seen in modern deer.
"Fossils are always surprising us. Now they show us unexpectedly that 270 million years ago two forms of interspecific combat represented in deer today, were already present in the forerunners of mammals," Cisneros concluded.
The findings were published in a recent edition of the journal Royal Society Open Science.
