At one point, Jack Horner suggested, based mostly on skull features, that hadrosaurids actually formed two more distantly related groups, with "Iguanodon" on the line to the flat-headed hadrosaurines, and "Ouranosaurus" on the line to the crested lambeosaurines, but his proposal has been rejected. The cladogram below follows an analysis by Andrew McDonald, 2012. Because "Iguanodon" is one of the first dinosaur genera to have been named, numerous species have been assigned to it. While never becoming the wastebasket taxon several other early genera of dinosaurs (such as "Megalosaurus") became, "Iguanodon" has had a complicated history, and its taxonomy continues to undergo revisions. Although Gregory Paul recommended restricting "I. bernissartensis" to the famous sample from Bernissart, ornithopod workers like Norman and McDonald have disagreed with Paul's recommendations, except exercising caution when accepting records of "Iguanodon" from France and Spain as valid. anglicus" was the original type species, but the lectotype was based on a single tooth and only partial remains of the species have been recovered since. In March 2000, the International Commission on Zoological Nomenclature changed the type species to the much better known "I. bernissartensis", with the new holotype being IRSNB 1534. The original "Iguanodon" tooth is held at Te Papa Tongarewa, the national museum of New Zealand in Wellington, although it is not on display. The fossil arrived in New Zealand following the move of Gideon Mantell's son Walter there; after the elder Mantell's death, his fossils went to Walter. Only two species assigned to "Iguanodon" are still considered to be valid. One of the first details noted about "Iguanodon" was that it had the teeth of a herbivorous reptile, although there has not always been consensus on how it ate. As Mantell noted, the remains he was working with were unlike any modern reptile, especially in the toothless, scoop-shaped form of the lower jaw symphysis, which he found best compared to that of the two-toed sloth and the extinct ground sloth "Mylodon". He also suggested that "Iguanodon" had a prehensile tongue which could be used to gather food, like a giraffe. More complete remains have shown this to be an error; for example, the hyoid bones that supported the tongue are heavily built, implying a muscular, non-prehensile tongue used for moving food around in the mouth.