8.7" Tyrannosaurus Rex Astragalus (Ankle Bone) - Montana

This is an 8.7" x 8" Tyrannosaurus rex astragalus (ankle bone) from the Hell Creek Formation of Carter County, Montana. This bone works in union with the other tarsus bones to support the bones superior to the ankle (nearly the entire dinosaur). There are multiple sections of gap fill, crack repair and restoration. The restoration to this bone is relatively minor, filling portions of bone that had broken and crumbled away at the point of repair. The most notable restoration is along the flat portion of this astragalus bone, where gap filling has occurred. Other points along the thickest portion of this bone have undergone crack repair and gap fill as well.

Based off of the size of this ankle bone, this Tyrannosaurus rex is estimated to have been around 6 meters (19.7 feet) tall and likely weighed upwards of 6 tonnes.