Location : Western U.S.

This may be the largest dinosaur ever. The only problem is that so little of Ultrasauros has been found it is hard to determine exactly what it may have looked like. The only thing that is certain is that it was a huge plant-eater and was related to Brachiosaurus  In fact, it may even be a really large Brachiosaurus 

This dinosaur has been through several descriptions since its discovery. Ultrasaurus, Supersaurus  and Brachiosaurus  have all been used to describe the remains - two bones, a vertebra and a scapulacoracoid. This last bone is almost 9 feet (2.7 m) long. There are enough subtle differences between similar bones in Brachiosaurus  to keep the debate going as to whether it should be a Brachiosaurus  species.