
From on high. Newly described fossils (inset) suggest that woolly rhinos evolved on the Tibetan Plateau about 3.7 million years ago.
Ice ages have struck North America and northern Eurasia every 100,000 years or so since about 2.8 million years ago. Many of the large creatures roaming the landscape during these cycles, including woolly mammoths, mastodons, and saber-toothed cats, mysteriously went extinct about 10,000 years ago, as the latest episode of global cooling waned. But when and where many of those megafauna originally evolved has been an even larger mystery, says Xiaoming Wang, a vertebrate paleontologist at the Natural History Museum of Los Angeles County in California.
In the new study, Wang and colleagues uncovered a variety of fossils - including a skull, a jawbone, and a couple of neck vertebrae in the Himalayan foothills along the southwest Tibetan Plateau. The plateau is often called "the roof of the world" because its 2.5-million-square-kilometer area - the largest and tallest in the world - has an average elevation that exceeds 4500 meters (14,800 feet). Based on the age of the sediments surrounding the fossils, which was estimated using the magnetic characteristics of the rock as well as the other fossils entombed therein, the researchers say the fossils belong to a new species of woolly rhino that roamed the region about 3.7 million years ago. The team has dubbed the rhino, which was about the size of its modern kin but covered with shaggy fur to help preserve its body heat, Coelodonta thibetana, or "the pit-toothed creature from Tibet."












