Scientists who study fossils are rarely able to find complete dinosaur
skeletons. This is especially true of the gigantic plant-eating dinosaurs, which were
commonly found without skulls. In order to complete a skeleton, scientists sometimes put
together fossil bones from different animals of the same species. Sometimes, however, they
make mistakes. In fact, the Carnegie Museum of Natural
History, like many other museums, displayed the Apatosaurus you
see below with the wrong skull for many years.