Aralosaurus

Aralosaurus is a genus of hadrosaurid dinosaur that lived during the Late Cretaceous in what is now Kazakhstan. It is known only by a posterior half of a skull (devoid of its mandible) and some post-cranial bones found in the Bostobe Formation in rocks dated from the Upper Santonian - lower Campanian boundary, at about 83.6 Ma (millions of years ago). Only one species is known, Aralosaurus tuberiferus, described by Anatoly Konstantinovich Rozhdestvensky in 1968. The genus name means "Aral Sea lizard", because it was found to the northeast of the Aral Sea. The specific epithet tuberiferus means "bearing a tuber" because the posterior part of the nasal bone rises sharply in front of the orbits like an outgrowth.

Aralosaurus was originally reconstituted with a nasal arch similar to that of North American Kritosaurus (a comparison based on a specimen now placed in the genus Gryposaurus). For many years, Aralosaurus was thus placed in the clade Hadrosaurinae. This classification was invalidated in 2004, following the re-examination of the skull of the animal which allowed to identify in Aralosaurus many typical characters of Lambeosaurinae. In particular, this study revealed that the genus had a hollow bony structure located far in front of the orbits, which communicated with the respiratory tract. However, this structure is broken at its base, so its shape and size remain undetermined. More recently, Aralosaurus has been identified as the most primitive lambeosaurine and placed with its close relative Canardia from the upper Maastrichtian of France in the new clade Aralosaurini.