Gobi jerboa by the Central Asiatic Expeditions and housed at the American Museum of Natural History (Allen 1925). Allen further compared the subspecies "Allactaga sibirica annulata" and "Allactaga sibirica sibirica", to the Gobi jerboa because they are all sympatric. Allen examined forty specimens collected from different regions of Mongolia, and found that while the Gobi jerboa was similar in color and appearance to "A. sibirica annulata", by exhibiting the same grayer and buffier phases, the Gobi jerboa has shorter and broader ears, smaller hind feet, and a much larger globular audital bullae (nearly three times the size), which differentiates it from "A.
Gobi Desert as a buffer against further desertification. The Gobi, broadly defined, can be divided into five distinct dry ecoregions, based on variations in climate and topography: The surface is extremely diversified, although there are no great differences in vertical elevation. Between Ulaanbaatar () and the small lake of Iren-dubasu-nor (), the surface is greatly eroded. Broad flat depressions and basins are separated by groups of flat-topped mountains of relatively low elevation ), through which archaic rocks crop out as crags and isolated rugged masses. The floors of the depressions lie mostly between above sea-level. Farther south, between Iren-dutiasu-nor and the Yellow