Abstract
The Late Cretaceous dinosaur-bearing localities discovered in the Ili River Basin in the foothills of Dzhungar Alatau, in the center of the historical region Zhetysu (Semirechie), in 1925–1927 are among the first occurrences for dinosaurs discovered in Asia. Preliminary identifications of dinosaurian remains from the Zhetysu localities, reviewed by Nesov (1995a), included Sauropoda, Tyrannosauridae, Hadrosauridae, Ankylosauridae, and possible Ceratopsidae. The only previously described specimen from this assemblage is a tibia attributed to cf. Ceratopsia by Riabinin (1939) from the Kara-Cheku locality. This bone is considered currently as Dinosauria indet. We describe here the most important find from this fauna to date, a partial tyrannosaurid dentary collected by a team from the Institute of Zoology of the Kazakh Academy of Sciences at the Kara-Cheku locality in 1950. This specimen can be confidently identified as a derived tyrannosaurine based on the incrassate teeth and the small first alveolus. This is the first record of a tyrannosaurine from the Late Cretaceous of Kazakhstan and Middle Asia. The age of Zhetysu dinosaur fauna is possibly Campanian or Maastrichtian.