bistahieversor
- Name meaning: Bistahi destroyer
- Length: 9-10.5 m( 30-33 ft )
- Weight: 3 tons
- Height: 3.8 m (13 ft)
- time period: 77-73.09 mya
- habitat: North America
- bite force: 8000 psi
- tooth length: 10-15 cm (4-5 in.)
Bistahieversor (meaning "Bistahi destroyer") is a genus of tyrannosaurid dinosaur. Bistahieversor existed in the Late Cretaceous. Hunter Wash member of the Kirtland Formation, which has been dated to 74.55 ± 0.29 Ma.
The name Bistahieversor comes from the Navajo Bistahí, or "place of the adobe formations" in reference to the Bisti/De-Na-Zin Wilderness where it was found, and eversor, meaning "destroyer.
Material from both adolescent and adult individuals has been found in the Kirtland Formation of New Mexico, United States. Adult Bistahieversor are estimated to have been around 9 metres (30 ft) long, weighing at least a ton. The snout is deep, indicating that the feature is not unique to more derived tyrannosaurs such as Tyrannosaurus. Geographical barriers such as the newly forming Rocky Mountains may have isolated the more southerly Bistahieversor from more derived northern tyrannosaurs.
Bistahieversor differs from other tyrannosaurs in the possession of 64 teeth, an extra opening above the eye, and a keel along the lower jaw. The opening above the eye is thought to have accommodated an air sac that would have lightened the skull's weight. Bistahieversor also had a complex joint at its "forehead" that would have stabilized the skull, preventing movement at the joint.