Abstract: Although highly diversified in their early history, only one genus in Ochotonidae,Ochotona, survives to the present. Ochotona is generally accepted to have originated from the Middle Miocene Bellatona. During the 2006–2010 field seasons, we found Miocene localities at Damiao, Siziwang Qi, Nei Mongol, which produced rich materials of ochotonids. Of these localities, DM01 (pliopithecid locality), dated by the paleomagnetic method and faunal comparison as late Middle Miocene (~12 Ma), yielded rich materials of the Bellatona-Bellatonoides-Ochotonagroup, and a large-sized relic form assigned to Desmatolagus moergenensis. The p3 morphology of the Bellatona-Bellatonoides-Ochotona complex conserves a similar tooth outline, but with distinct successive structures. The Bellatona form has two labial folds and no lingual fold on p3. The p3 ofBellatonoides form has one shallow anterolingual fold that is widely separated from the anterolabial fold. The p3 of Ochotona has a deep anterolingual fold that is closely connected with the anterolabial fold by a central bridge. The posterior process on M2 also shows progressive enlargement from Bellatona to Ochotona. Other cheek teeth of this complex are not distinguishable by either morphology or size. With only teeth found, we tentatively propose successive linear evolutionary relationships of the Bellatona-Bellatonoides-Ochotona complex, and Ochotona may have directly originated from Bellatonoides during the late Middle Miocene. The geological age of this fossil locality is consistent with the divergence time of Ochotona as estimated by molecular dating methods.