Sinotherium ("Chinese Beast") is a genus of single-horned elasmotheriine rhinoceros that lived from the late Miocene (Tortonian - Messinian) to Early Pliocene. It was ancestral to Elasmotherium, demonstrating a very important evolutionary transition from nasal-horned elasmotheriines to frontal-horned elasmotheriines. Its fossils have been found in the Karabulak Formation of Kazakhstan, lower jaw and teeth have been found in Mongolia, and a partial skull is known from the upper part of the Liushu Formation of western China. Sinotherium diverged from the ancestral genus, Iranotherium, first found in Iran, during the early Pliocene. Some experts prefer to lump Sinotherium, and Iranotherium into Elasmotherium. Discovery, History and Taxonomy Species The type species of Sinotherium is S. lagrelii. It is also known to have an additional species from the Zaisan depression of Kazakhstan called S. zaisanensis, however, doubt has been raised on its validity.<ref name="bayshashov1986"/ Discovery Finds of Sinotherium are rather rare and often only fragmentary. The first fossils, which also led to the description of the rhinoceros genus, came to light at the beginning of the 20th century and were discovered by JG Andersson in the Baode district in the Chinese province of Shanxi in deposits from the Upper Miocene. These mainly consisted of isolated teeth, but also an upper jaw fragment with the preserved row of teeth from the second premolar to the penultimate molar and a lower jaw fragment.<ref name="ringstrom1923"/<ref name="ringstrom1924"/ From north-western Mongolia near Chono-Khariakha, a 72 cm long, well-preserved lower jaw was discovered which dates to the Lower Pliocene.<ref name="kondrashov2000"/ Other individual finds are known from Kazakhstan, including a rear part of the skull with part of the teeth and several skeletal elements of the body. The most complete skull to date was found in the upper area of the Liushu Formation near Houaigou in the Guanghe District of Gansu Province. The Liushu Formation is about 100 m thick and over wide ranges of Linxia basin digested. This section is dated to about 7 to 6.4 million years and thus belongs to the end of the Miocene. The geological deposits of the Linxia Basin have already produced numerous well-preserved fossil rhinoceros remains, including numerous representatives of the Elasmotheria. Only the part of the snout is missing from the skull and it provided evidence of the location of the horns in Sinotherium. Description Skull and Horn The horns of older elasmotheriines are present on their nasals (nose), whereas the horn