New Mexico tibia hints at an earlier, giant tyrannosaur lineage in North America

Researchers in New Mexico uncovered a 96 cm tibia from a huge tyrannosaurid dating to about 74 million years ago, suggesting giant tyrannosaurs existed earlier than previously thought. Weighing roughly 4–5 tons, the specimen—found in the Hunter Wash Member of the Kirtland Formation—may be the oldest giant tyrannosaur in North America and is thought to belong to an early Tyrannosaurini lineage, shedding light on where these predators first evolved and how southern North American dinosaur populations differed from northern ones.