For the last seven months, the National Park Service been trying to put out a fire in a 25,000-year accumulation of giant Shasta sloth dung in a remote Grand Canyon cave.

So far, the agency has not succeeded, and the effort has cost $50,000.

The prehistoric pile, apprently ignited by hikers and discovered ablaze July 14, has been a treasure trove for paleobiologists and botanists since the cave and its contents were discovered in the 1930's.

The arid Arizona climate had preserved intact the dung and other remains of the Shasta sloth, which became extinct 12,000 years ago; an extinct species of mountain goat and other fauna and flora that flourished in the Southwest between 35000 and 8000 B.C.

Last summer park service and Interior Department mine safety officials journeyed to the cave by boat and helicopter, pumped it full of carbon monoxide and dioxide gases, and sealed it hoping the fire would die out.

When the cave was reopened late last month and found full of smoke, the dung smoldering like a bog or peat fire, frustrated government officials began considering other expensive alternatives.

Interior officials will meet Friday with University of Arizona professors, who have been digging in the dung for more than a decade, to discuss filling the fave with fire-fighting foam or hiring crews to shovel out the burning dung and shore up the cave's roof, which has been weakened by the fire.

Smithsonian Institution paleobiology curator Dr. Clayton Ray yesterday called the cave and its endangered feces a "unique stratified storehouse" of information. The Smithsonian's Museum of Natural History, which has a collection of Shasta sloth bones and dung, though not on display, conducted an expedition at the cave in 1940.

Ray said the Shasta sloth - which he does not like tocall a giant sloth "because he was only about the size of a black bear, nothing huge" - was not very notable except for producing a large and durable stool in the same place for about 25,000 years.

The radiocarbon method of dating living matter, discovered in the 1950s, has enabled scientists to record fairly precisely the latter years of the Shasta sloth, and its dry, almost mummified dung has helped determine its diet, Ray said.

The Shasta sloth died out just after the last ice age, at the same time most mammoths, mastodons, saber-tooth tigers, camels, horses and many species of wolf, sloth and other large mammals in North America became extinct, according to Dr. Paul Martin, University of Arizona professor of geosciences who calls himself, the "World's leading expert on fossil sloths.

Martin said the sluggish sloth's demise, like that of many other large America mammals, "coincided with the arrival of big-game hunters on the continent from Asia" about 10,000 to 12,000 years ago. Martin has been leading expeditions of university students to Rampart Cave every spring since 1969.

When last spring's dung dig ended, the iron gate on the cave, installed by the park service when the cave was discovered, was closed and locked. When the fire was first noticed in July, the park service found that the gate had been he aside.

Martin said he hopes the fire can be extinguished before it totally destorys the prehistoric dung "because there are only 10 known caves of sloth dung in the world, eight in North America and two in South America, and this is by far the best deposit . . . It's five feet thick"