Middle Miocene Ochotonids found from Siziwang Qi, Nei Mongol

August 13, 2012, Institute of Vertebrate Paleontology and Paleoanthropology
Middle Miocene Ochotonids found from Siziwang Qi, Nei Mongol
Cheek teeth in occlusal view of Desmatolagus moergenensis from DM01 locality, Nei Mongol. Image: ZHANG Zhaoqun

Ochotonids (commonly called pikas) are a group of small-sized lagomorphs, placed in the family Ochotonidae, and are most diversified in Asia, with only two species in North America and one in Europe. Though numerous fossil species have been found, only one genus of Ochotonidae, Ochotona, survives to the present. Fossil records indicate Asia was the center of origin for Ochotonidae. However, the divergence time of Ochotona is still unclear.

from Institute of and (IVPP), , and Department of Geosciences and Geography, University of Helsinki, found rich materials of ochotonids from Miocene localities at Damiao, Siziwang Qi, Nei Mongol during the 2006–2010 field seasons. Researchers reported the Bellatona-Bellatonoides-Ochotona group from one of these localities, DM01 (pliopithecid locality), which was dated as late Middle Miocene by the paleomagnetic method and faunal comparison, helping better understand the evolution of Ochotonidae and the origin of Ochotona.

Although no skulls or well preserved jaws of ochotonids were discovered from DM01, researchers identified four species of ochotonids based on isolated teeth: Desmatolagus moergenensis, Bellatona cf. B. forsythmajori, Bellatonoides eroli, and Ochtona cf. O. lagreli.

Selected cheek teeth in occlusal view from DM01 locality, Nei Mongol. A-C, L-M, P-Q, Bellatona cf. B. forsythmajori; D-F, Bellatonoides eroli; G-K, Ochotona cf. O. lagreli;: N-O, , R-S, Ochotonidae gen. et sp. indet. Image: ZHANG Zhaoqun

Desmatolagus moergenensis found from the Lower and Upper Miocene localities at Damiao have similar dental morphology as those from the DM01. Similar specimen was also found previously from Early to Late Miocene localities in the Aoerban area. Therefore, Desmatolagus moergenensis can be considered as a relic species of the which was flourishing during the Late Eocene and Oligocene and survived to the Late Miocene.

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 of Bellatonoides 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.

As other cheek teeth of this complex are not distinguishable by either morphology or size, and no skulls or well preserved jaws of ochotonids have been found so far, researchers tentatively proposed successive linear evolutionary relationships of the Bellatona-Bellatonoides-Ochotona complex, and Ochotona may have directly originated from Bellatonoides during the late Middle Miocene.

Preliminary magnetostratigraphic stuy indicates that the DM01 locality occurs about 12−12.4 million years ago, confirmed by faunal comparison with the classical Middle Miocene Tunggur faunas, which were paleomagnetically dated from11.8 to 13 million years ago.

According to Dr. ZHANG Zhaoqun of the IVPP, lead author of the study that appeared in the latest issue of Vertebrata PalAsiatica 2012(3), “The geological age of the DM01 locality is consistent with the divergence time of Ochotona estimated by molecular dating methods, suggesting the origin of Ochotona occurred around 12 to 13 million years ago, if not much earlier”.

Explore further: New cervid species found in middle miocene of Nei Mongol, China

Related Stories

New species of Nannocricetus found in Damiao of Nei Mongol

June 10, 2011

Dr. Zhang Zhao-Qun, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, and his colleagues, recently described a new cricetid species of Late Miocene, Nannocricetus wuae, from the locality ...

Tiny teeth are new mouse species, a rare 'living fossil'

May 24, 2011

(PhysOrg.com) -- Tiny fossil teeth discovered in Inner Mongolia are a new species of birch mouse, indicating that ancestors of the small rodent are much older than previously reported, according to paleontologist Yuri Kimura, ...

Recommended for you

Lifting barriers to citizenship for low-income immigrants

January 15, 2018

Taking the Oath of Allegiance at a naturalization ceremony is an emotional moment for many immigrants, and for good reason: it is the culmination of an often arduous process and many years of striving. Citizenship also opens ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.