Deinocheirus

When paleontologists were finally able to assess Deinocheirus in its entirety, they could see that the rest of this dinosaur lived up to the promise of its enormous hands and arms. A full-grown Deinocheirus measured anywhere from 35 to 40 feet from head to tail and weighed as much as seven to ten tons. Not only does this make Deinocheirus the largest identified "bird mimic" dinosaur, but it also puts it in the same weight class as distantly related theropods like Tyrannosaurus Rex!