The type species, A. remotus is known from a partial skull and three foot bones recovered from the Mongolian Nemegt Formation, which was deposited in a humid floodplain about 70 million years ago.

Its relationships to other tyrannosaurid genera were at first unclear, with some evidence supporting a hypothesis that Alioramus was closely related to the contemporary species Tarbosaurus bataar.

Known specimens were smaller than other tyrannosaurids like Tarbosaurus bataar and Tyrannosaurus rex, but their adult size is difficult to estimate since both Alioramus species are known only from juvenile or sub-adult remains.

A joint Soviet-Mongolian expedition to the Gobi Desert in the early 1970s found these remains at a locality known as Nogon-Tsav in the Mongolian province of Bayankhongor, Nemegt Formation.

[2][8] At the back of the skull there is a protrusion, called the nuchal crest, arising from the fused parietal bones, a feature shared with all tyrannosaurids.

[6] A cladistic analysis published in 2003 found Alioramus could be further classified into the family Tyrannosauridae and the subfamily Tyrannosaurinae, alongside Tyrannosaurus, Tarbosaurus and Daspletosaurus.

[12] A 2004 study supported this result but suggested it was equally probable that Alioramus belonged outside the family Tyrannosauridae entirely, with its supposed juvenile characters actually reflecting a more basal position within Tyrannosauroidea.

The long and low shape of the only known Alioramus remotus skull indicated that it was immature when it died and might even have been a juvenile Tarbosaurus, which lived in the same time and place.

The more prominent nasal crests and much higher tooth count of Alioramus, however, suggested it was a separate taxon, even if it is known only from juvenile remains,[10] confirmed by the discovery of A.

This would also suggest that both Alioramus and Tarbosaurus—whose remains have also been collected at the Tsagan Khushu locality, making them sympatric—used different feeding strategies, avoiding competition.

Furthermore, Alioramins seemingly remained confined to Asia, suggesting some factor prevented them from colonizing the better-sampled fossil deposits from North America.

[18] Histological analyses performed on the holotype of A. altai (IGM 100/1844) by Brusatte and colleagues in 2009 determined that this individual had an internal bone structure corresponding to a nine year-old and actively growing Tyrannosaurus.

Lastly, Brusatte and team argued against the skull shape and cranial ornamentation of Alioramus being juvenile traits, given that: IGM 100/1844 is smaller and slender than comparably aged Tyrannosaurus and has a longer snout than any known juvenile of large tyrannosaurids (Albertosaurus or Tarbosaurus); and several well-documented ontogenic (growth) series of other dinosaurs evidence that ornamentation increases throughout growth.

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.

[2] 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.