known from juvenile specimens in different growth stages, and that Qianzhousaurus represents an adult example of the alioramini. The examinations also suggest that the variation seen between the various species is consistent with the growth trends seen in other tyrannosaurid genera, though specimens that could constitute a full growth series from infant to adult for each species have not been recovered for any of these tyrannosaurs. One part of the growth series across all specimens in this study was discovered to remain unique to alioramin tyrannosaurs; the rugose process of the jugal starts small and conical in early life, but becomes massive and indistinct as the animals grow. This same study also suggests Alioramins did not undergo a secondary metamorphosis from slender juveniles to robust adults like other tyrannosaurs such as Tarbosaurus and Tyrannosaurus did, but maintained a unique physiology better suited to pursuit of fast, small prey. Paleoenvironment The Beds of Nogon-Tsav are considered to be the same age as the Nemegt Formation. This geologic formation has never been dated radiometrically, but the fauna present in the fossil record indicate it was probably deposited during the Maastrichtian stage, at the end of the Late Cretaceous. The Maastrichtian stage in Mongolia, as preserved in the Nemegt Formation and at Nogon-Tsav, was characterized by a wetter and more humid climate compared with the semi-arid environment preserved in the earlier, underlying Barun Goyot and Djadochta Formations. Nemegt sediments preserve floodplains, large river channels and soil deposits, but caliche deposits indicate periodic droughts. This environment supported a more diverse and generally larger dinosaur fauna than in earlier times. Kurzanov reported that other theropods, including Tarbosaurus, ornithomimosaurs and therizinosaurs were discovered at the same locality, but these remains have never been reported in detail. If the Nogon Tsav fauna was similar to that of the Nemegt Formation, troodontid theropods, as well as pachycephalosaurs, ankylosaurids and hadrosaurs would also have been present. Titanosaurian sauropods were also potential prey for predators in the Nemegt. See also Timeline of tyrannosaur research References External links 3D holotype braincase of A. altai at DigiMorph Tyrannosaurids Maastrichtian life Late Cretaceous dinosaurs of Asia Cretaceous China Fossils of China Fossils of Mongolia Nemegt fauna Fossil taxa described in 1976 Taxa named by Sergei Kurzanov