A new study has been released that pre-dates T-rex, with a new relative called Tyrannosaurus Mcraeensis which was around in New Mexico up to 7 million years before T-rex!
The new dinosaur was similar in size and weight to the more recent T-rex but the two main differences is the lower jaw is much more delicate in the Mcraeensis so it would have less bite than it's younger descendant. Also there was no ridge over the eyes of the T-Mcraeensis leading to a much more subtle appearance.
Image from twitter.com/Arturo Garcia.