The Late Cretaceous multituberculate mammal Kryptobaatar dashzevegi Kielan-Jaworowska, 1970 is the most common mammalian taxon in the Upper Cretaceous (?lower Campanian) rocks of the Djadokhta Formation at Bayan Zag (= Bayn Dzak) and Tögrög (= Toogreek), and in the beds of Ukhaa Tolgod in the Gobi Desert. Kryptobaatar is also common in the Bayan Mandahu Formation (equivalent of the Djadokhta Formation), Inner Mongolia, China, represented there by K. mandahuensis. Kryptobaatar has not been reported as yet from the younger (?upper Campanian) Baruungoyot Formation nor from its stratigraphic equivalents, the red beds of Hermiin Tsav (= Khermeen Tsav). In this paper we report the discovery of an incomplete skull of Kryptobaatar dashzevegi at Hermiin Tsav I. It is the second mammal species common to the Djadokhta and Baruungoyot Formations (the first being Deltatheridium pretrituberculare). We provide a corrected list of mammals found in the Late Cretaceous localities of the Gobi Desert, and we argue (albeit inconclusively), that mammal evidence shows that the Ukhaa Tolgod beds might be closer in time of deposition to the Djadokhta Formation than to that of the Baruungoyot Formation.

Key words: Mammalia, Multituberculata, Kryptobaatar, Deltatheroida, Cretaceous, stratigraphy, Gobi Desert.

Zofia Kielan−Jaworowska [zkielan@twarda.pan.pl], Instytut Paleobiologii PAN, ul. Twarda 51/55, PL−00−818 Warszawa, Poland; Jørn H. Hurum [j.h.hurum@nhm.uio.no], Paleontologisk Museum, Boks 1172 Blindern, N−0318 Oslo, Norway; Demchig Badamgarav [badamgr@yahoo.com] Paleontological Center of the Mongolian Academy of Sciences, 63 Enkh Taivani Gudamji, Ulaanbaatar 210351, Mongolia.