The fossilized remains were remarkably well preserved. The skull is just over four feet long (127 centimeters), while the whole animal would have been about 36 feet long and weighed four metric tons.
His arms were two feet long, “so he’s literally half the length of his skull and the animal couldn’t have reached his mouth,” Makovicky said.
T. rex did not get his small arms from M. gigas. The latter became extinct 20 million years before the former emerged, and the two species were far apart in the evolutionary tree.
In contrast, the authors believe that the fact that tyrannosaurids, carcharodontosaurids (the group to which Meraxes belonged) and a third species of giant predator called abelisaurids evolved all tiny arms points to certain benefits.