A controversial taxon, Hipparion plocodus, is reviewed in the present study. Hi. plocodus has been confirmed to be a valid species with definite diagnostic characteristics, represented by cranial specimens from Baode, Shanxi Province. The phylogenetic analysis performed in the present study, with a new matrix, shows that Hi. plocodus forms a monophyletic group with a European species, Hippotherium malpassii. Actually, no close relationship between so-called Hm. malpassii and the genus Hippotherium has been identified, and the record of stratigraphic range of this genus in late stage of Late Miocene is currently absent. Herein previously Hi. plocodus and Hm. malpassii have both attributed into “Hipparion” before the discovery of better material. Evolutionary stages and correlative absolute age showed that these two species should derive independently from some primitive clade. During the late stage of the Late Miocene, the development of the Asian summer monsoon enhanced the humidity of China, with forest and wood habitats expanding considerably under this setting. As the result, one Eurasian closed-habitat lineage thus extended its range into China, which had become very suited for it, give rise to “Hi.” plocodus.
