The Gobi Desert is famous for providing one of the worlds best preserved Cretaceous terrestrial faunas, including dinosaurs and mammals. Beginning with the Central Asiatic Expeditions in the 1920s, through the Polish-Mongolian Expeditions in the 1960s-1970s, Soviet-Mongolian Expeditions in 1970s, and finally the Mongolian Academy-American Museum Expeditions in the 1990s-2000s, the number of complete skulls (see Kielan-Jaworowska et al. 2000 for review) of Cretaceous mammals often associated with postcranial skeletons, found in Mongolia increased to several hundred. In addition to these professional expeditions, there have been other types of trips to Mongolia, also aimed at collecting fossils. The Nomadic Expeditions Company in USA organizes one of these, and has made trips to Mongolia since 1996. During the 1999 Nomadic Expedition, a skull associated with parts of the postcranial skeleton of the multituberculate mammal Catopsbaatar catopsaloides was found. The specimen is more complete than others previously known of this species and brings new data on multituberculate anatomy and ontogenetic variation. In this note we discuss the new data on the structure of C. catopsaloides; the details of its anatomy will be described in subsequent papers by the two first authors.

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; Philip J. Currie [philip.currie@gov.ab.ca], Royal Tyrrell Museum of Palaeontology, PO Box 7500, Drumheller AB T0J 0Y0, Canada; Rinchen Barsbold [barsgeodin@magicnet.mn], Institute ofGeology , Mongolian Academy ofSciences, Ulaanbaatar 210351, Enkh Taivani Gudamji, Mongolian People’s Republic.