A worn dinosaur tooth of a pantyrannosaurian, possibly an indeterminate tyrannosaurin or tyrannosaurid from the Iren Dabasu Formation in Erlian Basin, Inner Mongolia, China. The tooth, while labeled as Alectrosaurus, appears to be oddly robust, almost like a Tyrannosaurus rex with an oval cross-section. The tooth has a crown height of 24mm, CBL of 12.2mm, and CBW of 8.4mm. While the denticles are worn, the midline distal serration density is around 13/5mm, while what little remains of the mesial serration is around 9.5/2mm. This gives a odd DSDI of 1.8 like a dromaeosaurid, though the mesial density may be towards the base of the carinae which tends to be finer in theropods. Though the dinosaur fauna found in this deposit appear to be basal indicating a Cenomanian to Coniacian age, other studies suggest it may be Campanian to Maastrichtian. It is unclear if this represents a late surviving basal assemblage of animals, or a typical one of its age. Material from the Iren Dabasu previously assigned to Alectrosaurus may point towards a more derived animal similar to that of Raptorex kriegsteini present, which has been controversially debated as either, a valid immature tyrannosaurid or tyrannosaurin taxon, or a juvenile Tarbosaurus species. Another possibility is the potentially similar aged Khankhuuluu mongoliensis from the Bayanshiree (Bayan Shireh) Formation that was also previously assigned to Alectrosaurus. It's possible that the tooth belongs to a cf. Khankhuuluu sp. or similar tyrannosaur found in the Iren Dabasu. The actual age of the Iren Dabasu Formation will likely be relevant in the identification of teeth here. That said, the certainty of the provenance is unclear. While Timurlengia euotica teeth from the Bissekty Formation in Uzbekistan are something erroneously sold as Alectrosaurus or Iren Debasu tyrannosaur, this specimens appears to be, or probably from the Iren Dabasu Formation.
