Remains of Mastodon Reveal Diet : Paleontology: Stomach analysis differs from earlier theories. Bacteria from animal may be 11,000 years old.

Ohio researchers have excavated an 11,000-year-old mastodon with its stomach and intestinal contents intact, providing the first good evidence about what the species ate and clues as to why the massive animals became extinct.

The researchers also said Friday that among the contents of the intestine were living bacteria. “This could be the oldest living organism ever isolated,” said microbiologist Gerald Goldstein of Ohio Wesleyan University. But other researchers said it was more likely that the bacteria could not survive that long and are a contaminant of more recent origin.

The skeleton was unearthed from a peat bog in December, 1989, during the construction of a water hazard on the 15th hole of Burning Tree Golf Course in Newark, Ohio, and is in exceptionally good condition.

Mastodons were massive, hairy creatures distantly related to modern elephants, but with shorter trunks and longer tusks. They ranged from Alaska to Florida but were most common in Eastern forests. Remains of more than 150 have been found in Ohio, but few are complete and none contained intestinal material.

By measuring the growth rings in its tusks, researchers estimated that the Burning Tree mastodon was about 30 years old at the time of its death, according to biologist Daniel C. Fisher of the University of Michigan, an expert on mammoths. It stood about 9 feet tall at the shoulders and weighed perhaps 4 tons. The tusk growth rings and the contents of its stomach suggest that it died in late autumn.

The recovered skeleton is complete except for the right rear leg, a few tail bones and the toes. Healed injuries on the lower spine and right rib cage indicate that it had been in battles with other mastodons.

The mastodon was apparently butchered by humans, Fisher said, because it had marks on the ribs and other bones made with a stone knife. They must have butchered it elsewhere, “stashed it in the cold water of the pond that used to be there to preserve it, then for some reason never came back to reclaim it,” said archeologist Bradley Lepper of the Ohio Historical Society.

“In the course of the excavation, we found a concentration of red-brown material under the rib cage among the black peat that we believe, on the basis of location and smell, was intestinal components,” Lepper said.

“It smelled god-awful,” he added.

Studies by anthropologist Dee Anne Wymer of Bloomsburg University indicated that the intestines contained a broad variety of vegetation, including swamp grass, leaves, moss, and seeds of sedges, waterlily and other wetland vegetation.

“It must have been feeding very much like a moose, wading around in the water and feeding on the lush vegetation,” Lepper said. “That will be a surprise for a lot of people.”

In fact, many textbooks say that the mastodons lived largely on branches and needles from spruce pine, an idea based on the discovery of less well-preserved stomach contents in earlier skeletons. One theory for their extinction is that they starved when spruce pine forests died back during a period of climatic change. “This pretty well eliminates that theory,” Fisher said.

The most common theory for the demise of the mastodons is that they were hunted to extinction by humans.

The most surprising Ohio discovery was the isolation of bacteria from the intestinal matter. Goldstein cultured the matter in his laboratory and isolated Enterobacter cloacae, which is common in the intestines of mammals but rare elsewhere in the environment. Samples from the soil and water around the intestinal mass did not contain the bacteria, he said, indicating that it came from the intestines.

Goldstein speculated that the bacteria had remained dormant for 11,000 years because of the cold, oxygen-free environment in which they were trapped. Those conditions also preserved the plant material in the intestines.

But others were less willing to concede the origin of the bacteria, speculating that they were contaminants. “What proof do they have?” asked bacteriologist Carl Woese of the University of Illinois at Urbana-Champaign. “If you’re not privy to the evidence, you’ve got to be skeptical.”

Bacteria “theoretically survive for that length of time, but it would be very unusual,” said UCLA microbiologist Patricia Hartzell. “I can’t cite any evidence that that kind of bacteria can survive that long.”

Goldstein is now analyzing the bacteria to determine if they differ from their modern-day counterparts. If they do, he said, “they could serve as a yardstick to measure the evolution of bacterial life.”