now just has Iguanodon . Iguanodon lies between Camptosaurus and Ouranosaurus in cladograms, and is likely descended from a camptosaur-like animal. [2] At one point, Jack Horner thought, based on skull traits, that hadrosaurids formed two more distantly related groups, with Iguanodon on the line to the flat-headed hadrosaurines , and Ouranosaurus