The Wounded Mastodon

By Gail Jarrow ~ Illustrated by John Rice

What killed this Ice-Age creature?
During prehistoric times, shaggy-haired mastodons roamed North America. Near the end of the last Ice Age, one of these elephant-like animals collapsed and died. Sediment gradually covered the six-ton male’s body. Over many years, the rest of its kind went extinct.

Eleven thousand years passed. Then, in 1866, workers unearthed the mastodon’s skeleton while they were digging a building foundation in Cohoes, New York. The skeleton was displayed in the New York State Museum in Albany, where visitors can still view it today. People wondered what had killed the Cohoes mastodon. Yet the answer remained a mystery until a scientist noticed some important clues.

Dr. Daniel Fisher studies the fossil remains of mastodons to learn how they lived and died. He has examined the bones of dozens of mastodons. When he studied the Cohoes mastodon, he noticed that it shared something unusual with five other mastodon skeletons he had seen in other places: all of them had serious injuries to the skull. These injuries usually killed the animal immediately.

A Mysterious Death
The injured Cohoes mastodon didn’t die right away, however. A blow to its skull caused an infection that prevented it from eating. Based on the growth of the mastodon’s teeth and tusks, Dr. Fisher says, “The animal seems to have lived for almost a month before starving.”

After examining the broken bones of the six mastodon skeletons, Dr. Fisher suspected that a strike from another mastodon’s tusk had caused the wounds. Mastodons had sturdy skeletons. It seems that they were stronger than today’s elephants. An attacking mastodon would have had the strength to thrust its six-foot-long tusk through an opponent’s thick hide and muscles. “Their tusks could have inflicted enormous damage,” says Dr. Fisher.

But why would mastodons attack one another? Dr. Fisher looked to the mastodon’s relative, the modern elephant. Adult male elephants sometimes fight with other males when they are ready to breed—a time called musth. To chase away its rival, a male elephant uses its tusks as weapons. Battles can end in death unless the weaker male backs down.

Clues in the Skull
Dr. Fisher found signs that male mastodons also used their tusks in battles with other males. A mastodon’s tusk grew in a socket in the skull. The socket contains pits where thick fibers, called ligaments, had been attached when the animal was alive. The ligaments, which decayed long ago, had held the huge tusk in place. In adult males, the pits in one area of the tusk socket are larger than in females. That means that in this part of the socket, the tusk ligaments were thicker in males.

Both male and female mastodons probably used their tusks to pry off branches and push over small trees as they ate leaves and twigs. They also would have used the tusks to slam sideways against attacking predators. But adult male tusks must have had an additional purpose that required extra support.

Dr. Fisher thinks that the other purpose was to fight rival males the way elephants do. The ligaments acted as a shock absorber when the male mastodon thrust its tusk tip into an opponent. “It probably happened everywhere there were mastodons,” he says. “Male-male combat seems to be part of the normal picture of life in these animals.”

Had each of the six mastodons received its wounds while it was in musth? Dr. Fisher had reasons to think they had. The Cohoes mastodon and all five of the others were males of breeding age. Dr. Fisher had never seen the same serious wounds in skeletons of females or young males.

The Tusks Tell a Tale
The mastodons’ tusks held more clues. Tusks have growth rings, the way tree trunks do. The rings are a diary of the mastodon’s life. When rings are wide, they show a time when the mastodon was eating well and growing quickly. When the rings are narrow, the animal was growing slowly. Like modern elephants, mastodons in musth probably ate very little, causing their tusks to grow slowly.

In the six injured mastodons, the tusk rings were narrow during the period before each animal died. Dr. Fisher believes, therefore, that the mastodons had been in musth when they were injured. He concluded that each one had been wounded by the tusk of another male.

A Battle on Computer
Yet how could a male mastodon use its curved tusk to attack its rival? A straight thrust would not cause the injuries found in the six skeletons.

To demonstrate how the injuries might have happened, Dr. Fisher used three-dimensional computer models of two fighting mastodons. After testing his computer mastodons in different attack positions, he showed how the injuries could have occurred. The attacking male must have lowered its head, then swept up as it rammed the tusk tip into the opponent’s skull.

By studying bones, Dr. Fisher concluded that the Cohoes mastodon had lost a deadly battle with a rival male. In solving the mystery, Dr. Fisher brought a moment of prehistory back to life.

Dr. Fisher of the University of Michigan used a computer to create this image and others. The movements of these computer-generated skulls showed how the mastodon received its deadly injury.

Click here to see Dr. Fisher's video of fighting mastodon skulls.