When I was first becoming acquainted with dinosaurs during the latter half of the 1980’s, the standard “rule” for theropod dinosaurs was that as they grew bigger through the course of time their heads became more robust and their arms grew smaller. Just comparing the Jurassic predator Allosaurus with the Cretaceous Tyrannosaurus rex (numerous pictures of both filling the books I constantly begged my parents to purchase for me) seemed to confirm this, but there was always one very special set of fossil remains that seemed to contradict the prevailing trend. Hung up in the corner at the American Museum of Natural History in New York were a pair of gigantic forelimbs, about twice as long as I was tall