Older museums would deal really with the mere weight of the bones. As technology has proceeded, we have been able to accommodate the fragility of the bone as well as its weight and so we have a mount here where all the bones are removable.
We make a cast for several reasons. Someone else may want to study it. If someone comes to The Field Museum and wants to study Sue, the first thing we'll show them is a cast. And for a lot of people that will be good enough because these casts are very detailed. But we also made casts so that we could send traveling exhibits around the country and around the world so that other people can see Sue.