Deinocheirus

The only fossil of this dinosaur is a pair of arms. These arms look like they belonged to an ornithomimid but they were 8 feet long. This means that either Deinocheirus towered over the rest of the ornithomimids (and most theropods, since, regarding proportions, it would have been 40 feet long!) or it simply had very long arms for its body. The use of its arms is debated: some say it used them to tear apart large dinosaurs, others say that the claws were too blunt, so they were used as defensive weapons. Some have even said that Deinocheirus used its huge arms to climb trees, although this hypothesis is widely disregarded. Once again, the lack of a body leaves many questions unanswered.