Do you know your dinosaurs? Dan does. He and his dog Bouncer are digging down to see if they can find the Tyrannosaurus Rex that could swallow a boy in just two bites, the gigantic Brachiosaurus that was taller than the tallest trees, and the Coelophysis that had knife sharp teeth, and sometimes ate its own young. Dan finds a pin and a scrunched up tin, and an old plate and a key to a gate, and a stone that looks like an odd sort of bone. He doesn't think anything of the odd shaped stone until his mum drags him to the museum (which he's sure is going to be boring and musty) where he spies that the awesome Ty Rex skeleton has a tooth missing - just like Dan! He knows that dinosaurs grew new teeth when the old ones got broken...and the tooth gap looks just the right shape and size for it to be...the odd shaped stone!