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 paleontologists consider the skull to belong to a juvenile "Tyrannosaurus rex". There are minor differences between the two species, including the higher number of teeth in "N. lancensis", which lead some scientists to recommend keeping the two genera separate until further research or discoveries clarify the situation. Below is the cladogram of Tyrannosauridae based on the phylogenetic analysis conducted by Loewen "et al." in 2013. The identification of several specimens as juvenile "Tyrannosaurus rex" has allowed scientists to document ontogenetic changes in the species, estimate the lifespan, and determine how quickly the animals would have grown. The smallest known individual