T. rex Holotype

Despite their relatively puny arms, Tyrannosaurus rex had the jaw-dropping power of a 40-foot-long, 5-ton body. And their spiky teeth were sharp, efficient, and deadly. Roaming what is today the western U.S. and southwestern Canada in search of food, the meat-eating T. rex ruled some 68 to 66 million years ago during the late Cretaceous Period. But it wasn’t until 1902 that the holotype—the scientific name-bearing specimen and the one to which all others must be compared—was unearthed at Hell Creek, Montana. At the turn of the century, the competition among museums to discover and display dinosaur fossils was fierce. Young fossil hunter Barnum Brown was hired by New York’s American Museum of Natural History to lead its charge, and he did not disappoint. Over three years, he unearthed what was at the time a whole new species of dinosaur. But it didn’t take long before Brown moved on to bigger and better findings. His 1908 excavation of a more complete T. rex skeleton prompted the museum to move the holotype into storage, and in 1941, with a dwindling research budget, the American Museum sold the T. rex holotype to Carnegie Museum of Natural History. The price? $7,000 ($130,000 in today’s currency) for what is by definition the first fossil of the world’s most famous dinosaur.