Large Tyrannosaur Fossil from New Mexico Sheds Light on T. Rex Ancestry

A substantial dinosaur tibia discovered in New Mexico's Kirtland Formation, dated to 74 million years ago, suggests a sizable relative of Tyrannosaurus rex existed earlier than previously thought. Researchers, including paleontologists from the New Mexico Museum of Natural History and Science and the University of Bath, published findings on March 12 in Scientific Reports, indicating the bone belonged to an animal possibly weighing over 4.5 tons and measuring around 35 feet long. This challenges earlier assumptions that tyrannosaurs of that era were smaller, potentially supporting the idea that the Tyrannosaurus genus originated in North America. However, some experts, like Thomas Carr of Carthage College, propose the fossil might belong to a different genus, Bistahieversor, highlighting the need for further specimens to confirm its classification.