Here at The Field Museum, we often show our Chicago pride by outfitting our Brachiosaurus plastic mounted skeleton on the west side of the building with an oversized team jersey. Whenever we do this, it creates a flurry of questions and comments about why we don’t do this with SUE the T. rex, too. Here’s why you won’t see SUE decked out in festive attire.
It’s not a lack of interest in competitive sports: though SUE looks pretty tough, they're composed of real fossils (90 percent complete). In contrast, the Brachiosaurus is a weatherproof mounted “skeleton” made of plastic bones and a metal armature. The mount is a combination of plastic cast bones from The Field Museum’s holotype of Brachiosaurus altithorax and plastic sculpted bones based on the African giant, Giraffatitan brancai (a close relative of Brachiosaurus), in the Museum für Naturkunde in Berlin.
Despite being created based on two different but related real fossils, this particular plastic skeleton (and the same plastic skeleton found in the O’Hare Airport) is made from durable materials that make it possible to show them without having to worry about damage to real fossils.
SUE, on the other hand, is the real thing. The skeleton consists of real bones displayed on a special mount. This mount allows each bone to be removed for study so that all the details can be seen without the metal armature in the way. SUE is the most complete T. rex skeleton by bone volume, at 90 percent complete, which makes it important for us to take extra special care of them. Paleontologists from all over the world come to Chicago to study them. While their bones have been well preserved, they are still extremely delicate. For this reason, we won’t put any kind of material on their skeleton, thus avoiding any unnecessary risks. Our collection manager takes great lengths to care for SUE and ensure their safety so that visitors can see them and scientists can study them for years to come.Bill Simpson, Collection Manager, Fossil Vertebrates, contributed to this post.