DENVER — If a group of prominent ecologists have their way, lions and elephants could someday be roaming the Great Plains of North America.

The idea of transplanting African wildlife to this continent is being greeted with gasps and groans from other scientists and conservationists who recall previous efforts to relocate foreign species halfway around the world, often with disastrous results.

But the proposal’s supporters say it could help save some species from extinction in Africa, where protection is spotty and habitats are vanishing. They say the relocated animals could also restore the biodiversity in North America to a condition closer to what it was before humans overran the landscape more than 10,000 years ago.

Most modern African species never lived on the American prairie, the scientists acknowledge. But some of their biological cousins such as mastodons, camels and saber-toothed cats, roamed for more than 1 million years alongside antelope and herds of bison until Ice Age glaciers retreated and humans started arriving.

The rapid extinction of dozens of large mammal species in North America — perhaps due to a combination of climate change and overhunting — triggered a landslide of changes to the environmental landscape. Relocating large animals to vast ecological parks and private reserves would begin to repair the damage, proponents say, while offering new ecotourism opportunities to a withering region.

The scientists’ plan appears in today’s issue of the journal Nature. It is attracting interest from some influential circles, including media mogul Ted Turner, America’s largest private landowner. He owns huge ranches in several states to support his commercial bison operation and personal conservation initiatives.

The plan is generating criticism on both sides of the conservation debate.

“It is not restoration to introduce animals that were never here,” said University of Washington anthropologist Donald K. Grayson. “Why introduce Old World camels and lions when there are North American species that could benefit from the same kind of effort?”

Others wonder whether people would support African lions making a home on the range, given the opposition to the reintroduction of native wolves in the rural West.

“Just when you think the world has gotten as weird as it can get, something like this comes along,” said Steve Pilcher, executive vice president of the Montana Stockgrowers Association.

“I wonder how many calves or lambs it would take to feed a family of lions for a month?” Pilcher mused. “We sort of know what it takes for wolves, but something tells me we would be in a whole new ball game.”

Some wildlife conservationists said the idea would further damage the prospects of both threatened species and Africa’s hopes for sustainable economic development.

“Such relocations would affect future tourism opportunities for Africa,” said Elizabeth Wamba, the East Africa spokeswoman for the International Fund for Animal Welfare in Nairobi, Kenya. “The welfare of the animals would have been reduced by transporting and exposing them to different eco-climatic conditions.”

Critics also point to calamitous relocations of foreign species in Australia. Rabbits brought from Europe swarmed across parts of the Outback, and noxious cane toads brought from South America to control bugs in sugar cane fields killed native wildlife.

The authors of the new plan say they are not discouraged.

“We are not saying this is going to be easy,” said Cornell University ecologist Josh Donlan, the lead author of the proposal.

The plan grew from a retreat at Turner’s New Mexico ranch — a 155,000-acre property in the foothills of the Gila Mountains that contains a mix of ecosystems ranging from desert grasslands to pine forests.

Donlan concedes that lions would be a tough sell to Americans.

“Lions eat people,” he said. “There has to be a pretty serious attitude shift on how you view predators.”