White lemuroid possums—otherwise known as Hemibelideus lemuroides—may have become the first mammal to disappear because of climate change, according to an Australian researcher. The cute marsupials restricted to certain mountaintops in the prehistoric "Lost World" of far northern tropical Queensland, Australia, may have fallen victim to an average temperature rise of at least 1.2 degrees Fahrenheit (0.5 degrees Celsius) over the last several decades.

Nocturnal, fruit-eating creatures that live in old-growth trees, this rare white form of the marsupial was found in two mountain peak cloud forests—until 2005. Prior to that, such possums were often spotted during nighttime expeditions. But they have not been seen since a heat wave that year, biologist Steve Williams of the Centre for Tropical Biodiversity and Climate Change at James Cook University told Brisbane's Courier-Mail newspaper.

"It only takes four or five hours of temperatures above 30 [degrees Celsius (86 degrees Fahrenheit)] to kill this highly vulnerable species," Williams said. "They live off the moisture in the trees in the cooler, high-altitude cloud forests and, under extreme heat, they are unable to maintain their body temperature."

A thorough survey of the area in 2009 will provide the final verdict on the white possum's fate. But preliminary research suggests that species shifting up mountainsides in flight from global warming have seen the first of their cohort pushed to the brink of extinction, although scientists believe that less charismatic creatures, such as amphibians and insects, have probably already disappeared unnoticed.

Even if a remnant population of the white possum is found, it may prove difficult to save the species due to a lack of genetic diversity rendering the animal functionally extinct like the baiji or the fact that its habitat is found nowhere else in the world—a remnant of animals and plants that thrived hundreds of millions of years ago now reduced to a mountain-encircled river valley declared a World Heritage site in 1998.

"It was quite depressing going back on the last field trip a couple of weeks ago, going back night after night thinking 'OK, we'll find one tonight,'" Williams told the Australian Broadcasting Corporation (ABC). "But no, we still didn't find any."