Three-toed horses reveal the secret of the Tibetan Plateau uplift

The Tibetan Plateau is the youngest and highest plateau on Earth, and its elevation reaches one-third of the height of the troposphere, with profound dynamic and thermal effects on atmospheric circulation and climate. The uplift of the Tibetan Plateau was an important factor of global climate change during the late Cenozoic and strongly influenced the development of the Asian monsoon system. However, there have been heated debates about the history and process of Tibetan Plateau uplift, especially elevations in different geological ages. 

In PNAS Early Edition online April 23, 2012, Dr. Tao Deng from Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, and his team report a well-preserved skeleton of a 4.6 million-year-old three-toed horse (Hipparion zandaense) from the Zanda Basin, southwestern Tibet. Morphological features indicate that the Zanda horse was a cursorial horse that lived in alpine steppe habitats. Because this open landscape would be situated above the timberline on the steep southern margin of the Tibetan Plateau, the elevation of the Zanda Basin 4.6 Ma ago was estimated to be ~4,000 m above sea level using an adjustment to the temperature in the middle Pliocene as well as comparison with modern vegetation vertical zones. Thus, Deng and his team conclude that the southwestern Tibet achieved the present-day elevation in the mid-Pliocene.
Fossils of the three-toed horse genus Hipparion that have been found on the Tibetan Plateau have provided concrete evidence for studying the uplift of the plateau, including a skull with associated mandible of Hipparion zandaense from Zanda. In August 2009 a three-toed horse skeleton was excavated from the Zanda Basin, and its dental morphology confirmed the assignment to H. zandaense.
The Zanda Basin is a late-Cenozoic sedimentary basin located just north of the high Himalayan ridge crest in the west-central part of the orogen (32° N, 82° E). The Sutlej River has incised through to the basement, exposing the entire basin fill in a spectacular series of canyons and cliffs. The horse skeleton was discovered in the eastern bank of the main wash of Daba Canyon west of the Zanda county seat and south of the Sutlej River.
Because both morphology and attachment impressions on fossilized bones can reflect muscular and ligamentous situations, they can provide evidence for the type of locomotion that extinct animals used when they lived. The skeleton of the Zanda horse preserved all limb bones, pelvis, and partial vertebrae, which provide an opportunity to reconstruct its locomotive function.

 http://phys.org/news/2012-04-three-toed-horses-reveal-secret-tibetan.html