In 1998, a New Mexico fossil revealed a previously unknown Tyrannosaur that predated T. rex and roamed Earth 75 million years ago

​Dinosaur species older than T. rex: Paleontologists identified Bistahieversor sealeyi, a new tyrannosaur species from New Mexico. This dinosaur lived about seventy-five million years ago, predating T. rex by ten million years. Bistahieversor was much smaller than T. rex, weighing at least a ton. Its skull featured subtle differences, indicating primitive tyrannosaur characteristics.

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