The engines are asked to transport a complete dinosaur skeleton to Vicarstown and it's very important they keep the bones in the right order for the paleontologist.
A paleontologist has dug up a T-Rex skeleton in the old mines, and the Biggest Adventure Club are tasked with delivering it. However, they arrive out of order, and the skeleton is incomprehensibly jumbled until they figure out how to maintain the order the pieces were left in.