Loewen et al. described a new genus of tyrannosaurid theropod Lythronax and a new specimen of Teratophoneus, and constructed a large phylogenetic analysis containing most tyrannosauroids known at the time. Though the authors made a fascinating research here, however, some portions of this paper are containing incorrect or ambiguous datas.

Both diagnoses of Lythronax and Teratophoneus state that "differs from all other tyrannosauroids except (Teratophoneus or Lythronax) and Bistahieversor in the presence of 11 maxillary alveoli ". However, the holotype of Bistahieversor(NMMNH P-27469) clearly has 13 maxillary alveori [1], and some Tyrannosaurus specimens have 11 maxillary alveori as well [2].
Also, diagnosis of Lythronax states that "differs from all other tyrannosauroids except Tyrannosaurus and Tarbosaurus in having a laterally expanded caudal portion of the skull ". However, numerous authors have shown that one of the key differences between Tyrannosaurus and Tarbosaurus is much more narrow caudal portion of the skulls of Tarbosaurus [3].

The authors contained Raptorex in their phylogenetic analysis and stated it as a valid taxon, and stated its geological information as "Yixian Formation, Early Cretaceous" in their supplementary information. However, Raptorex is an invalid taxon based on smuggled fossil of juvenile tyrannosaurid(might be Tarbosaurus) from Nemegt Formation, Late Cretaceous [4].

Chan-gyu Yun

1. Thomas Carr. pers., comm.
2. Currie, Philip J.; Hurum, Jørn H.; and Sabath, Karol (2003). "Skull structure and evolution in tyrannosaurid phylogeny" (PDF). Acta Palaeontologica Polonica 48 (2): 227–234.
3. Hurum, Jørn H.; and Sabath, Karol (2003). "Giant theropod dinosaurs from Asia and North America: Skulls of Tarbosaurus bataar and Tyrannosaurus rex compared". Acta Palaeontologica Polonica 48 (2): 161–190.
4. Fowler DW, Woodward HN, Freedman EA, Larson PL, Horner JR (2011) Reanalysis of “Raptorex kriegsteini”: A Juvenile Tyrannosaurid Dinosaur from Mongolia. PLoS ONE 6(6): e21376.