Figure 3 A series of six elasmotheres species from the Middle Miocene to the Late Pleistocene. They display an increase in skull size and development from a nasal horn to a frontal horn. These skulls are reconstructed based on AMNH 26531 (Tunggur in Inner Mongolia, Middle Miocene) for Hispanotherium tungurense, HMV 0979 (Houshan in Guanghe, Gansu, Late Miocene) for Iranotherium morgani, HMV 1411 (Guonigou in Dongxiang, Gansu, Late Miocene) for Parelasmotherium linxiaense, HMV 1449 (Guonigou in Dongxiang, Gansu, Late Miocene) for Ningxiatherium euryrhinus, V 18539 (Huaigou in Guanghe, Gansu, Late Miocene) for Sinotherium lagrelii, and NHM 12429 (Sarepta in Russia, Late Pleistocene) for Elasmotherium sibiricum. Although the modern Indian and Javan rhinos have a single horn on their noses, the extinct one-horned rhino Elasmotherium was a source for the legendary unicorn, because the latter had a very long horn on its forehead and lived with the prehistoric human beings who drew its images on cave paintings. Elasmothere rhinos first appeared in South Asia in the Early Miocene, but the origin of Elasmotherium has been unclear. All other elasmotheres have a weak or strong nasal horn, whereas Elasmotherium seems to lose the nasal horn of its ancestors and to get a huge frontal horn apparently abruptly. Here we report the first discovered skull of Sinotherium lagrelii from the Late Miocene red clays in the Linxia Basin, northwestern China. This skull has an enormous nasofrontal horn boss shifted posteriorly and a smaller frontal horn boss, which are connected to each other, indicating an intermediate stage for the single frontal horn of Elasmotherium. Morphological and phylogenetic analyses confirm that Sinotherium is a transitional taxon between Elasmotherium and other elasmotheres, positioned near the root of the giant unicorn clade and originated in a subarid steppe. The posteriorly shifted nasal horn has a more substantial support and the arched structure of the nasofrontal area is an adaptation for a huge horn. Keywords: Rhinocerotidae, elasmothere, Sinotherium, Late Miocene, Linxia Basin Habitat reconstruction the Linxia Basin during the Late Miocene. Art: ~sinammonite on http://sinammonite.deviantart.com under guidance of IVPP scholar Deng Tao Deng T, Wang S Q, Hou S K. A bizarre tandem-horned elasmothere rhino from the Late Miocene of northwestern China and origin of the true elasmothere. Chin Sci Bull. doi: 10.1007/s11434-012-5574-4 http://124.16.247.212/bitstream/311034/2181/1/Deng%20et%20al%20Sinotherium.pdf