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
Raptorex its exact identity cannot be known without more information about growth patterns in tyrannosaurids, and further efforts to discover its age. Consequently, Sereno's hypothesis that the derived features of tyrannosaurids evolved in the Early Cretaceous cannot be supported by current evidence. Newbrey "et al." (2013) identified the fish vertebra centrum found with the holotype specimen of "Raptorex kriegsteini" as belonging to a hiodontid, probably representing the same taxon as hiodontid fossils described by the authors from the Late Cretaceous Nemegt Formation of Mongolia. According to Newbrey "et al.", centra like those of the Nemegt hiodontid are not known from outside