Mastodon Tusks Tell of Brutal Battles

Oct. 19, 2006 —Battle scars on male mastodon tusks reveal that the Ice Age giants fought in brutal combat each year during seasonal phases of heightened sexual activity and aggression, according to new findings that will be announced at this week's Society of Vertebrate Paleontology meeting in Ontario.

The discovery counters the view that now-extinct mastodons were peaceful, passive creatures that rarely engaged in battles.

It also strengthens the link between mastodon and modern elephant behavior, since male bull elephants also fight seasonal, hormonally-charged battles to show their dominance and win desired mates.

Like warriors with different weapons, however, the two animals had distinct fighting techniques, lead author Daniel Fisher, a University of Michigan paleontologist, told Discovery News.

"Mastodon tusks curve upward strongly at the tips and appear to have been used in a vigorous up-thrusting motion," explained Fisher, who added that elephant tusks are less curved and therefore tend to be used more "in a straight thrusting move."

Fisher's analysis of mastodon tusks and skulls revealed that such ramming caused the lower part of the tusk to rotate backward, "crunching it against the back wall of the tusk socket."

He found that although the tusk continued to grow by adding layers of ivory to its base, pitted scars line up along the outside curve of the tusk base.

"It's not just one event, but a whole series of events that is preserved in this tusk record of fighting," he said.

Using previous research about mastodon tusk growth patterns, Fisher also found the scars correspond to seasonal patterns — the pits formed each year of the adult male animal's life during mid-spring to early summer.

Studies on mastodon vertebrae also helped fill out a picture of gory battles between the 8 to 10-foot-tall creatures.

"For example, we have evidence of tusks stabbing into the vertebral column, penetrating the space traversed by the spinal cord, from a direction that implies the victim was already lying on his side on the ground; in other words, the violence went on, even after one animal was down," Fisher said.

Other fossils suggest some of the animals were butchered in autumn — likely by humans, who may have caused or contributed to the extinction of mastodons 11,000 years ago.

Jeffrey Saunders, curator and chair of geology at the Illinois State Museum, told Discovery News that he has excavated over 72 mastodons.

"I always viewed them as being rather passive animals because I never found many broken bones — maybe one or two broken ribs — but I greatly respect Dr. Fisher's work and I continue to be open-minded about the possibilities," he said.

Saunders, who once found himself between two fighting bull male elephants while in a small jeep, added, "I also think it's interesting that similarities between mastodons and modern elephants seem to persist, given that these animals parted evolutionary ways 40 million years ago. The basic elephant design must be successful to have persisted so long."