Structural evidence

Analysis of the structure of the 30cm-long fossilised hip (pubis) bone led to identifying the owner as a:

  • tyrant lizard - tyrannosauroid
  • tyrannosaurids and ancestor of Tyranosaurus rex

Structural features shared with tyrannosauroids:

  • Several distinctive synapomorphies indicate tyrannosauroid affinities
  • transversely narrow, parallel-sided pubic boot indicates referral to Coelurosauria
  • The pubic boot is large; its anteroposterior length is 0.45 times the pubic shaft length (a minimum estimate because the boot is broken).is comparable to those of tyrannosauroids and some basal coelurosaurs
  • This demonstrates that advanced tyrannosauroids with characteristic short arms and powerful jaws achieved a global distribution in the Early Cretaceous

Derived features shared with tyrannosaurids, specifically:

  • The pubis is almost identical to those of tyrannosaurids
  • The pubic tubercle is broken, but the preserved portion indicates a prominent, anterolaterally curving, flangelike morphology
  • The anterior expansion of the boot is substantial, as in tyrannosaurids
  • The length of NMVP186046 (307 mm) is only slightly longer than the pubis of Raptorex

The features features of the hip bone shared with tyrannosauroids and tyrannosaurid hip bones suggests a potentially cosmopolitan grade of small tyrannosauroids with a tyrannosaurid-like body plan preceded the Late Cretaceous rise of the colossal tyrannosaurids.