Raptorex Raptorex Raptorex is a dubious genus of tyrannosaurid dinosaur. Its fossil remains consist of a single juvenile specimen probably uncovered in Mongolia, or possibly northeastern China. The type species is "R. kriegsteini", described in 2009 by Sereno and colleagues. The genus name is derived from Latin ', "robber", and ', "king". The specific name honours Roman Kriegstein, a survivor of the Holocaust, whose son Henry Kriegstein donated the specimen to the University of Chicago for scientific study. While initially considered to have come from the Yixian Formation of China, dated to approximately 125 million years ago during the early Cretaceous
Tyrannosaurus has shown that it was much narrower than that of "Tyrannosaurus rex" and that during a bite, the distribution of stress in the skull would have been very different, closer to that of "Alioramus", another Asian tyrannosaur. A related cladistic analysis found that "Alioramus", not "Tyrannosaurus", was the sister taxon of "Tarbosaurus", which, if true, would suggest that "Tarbosaurus" and "Tyrannosaurus" should remain separate. The discovery and description of "Qianzhousaurus" in 2014, would disprove this and reveal that "Alioramus" belonged to the clade Alioramini. The discovery of the tyrannosaurid "Lythronax" further indicates that "Tarbosaurus" and "Tyrannosaurus" are closely related, forming