Researchers say they have identified a new subspecies thought to be an older and more primitive relative of the Tyrannosaurus rex. A team of paleontologists and biologists from several universities and the New Mexico Museum of Natural History and Science announced their findings Thursday. They say the discovery reshapes ideas about how T. rex first came to be in what is now North America by introducing its earliest known relative on the continent. Their work was based on a partial skull that was unearthed years ago in southern New Mexico. They determined the specimen predated T. rex by up to 7 million years.
