 I. lakotaensis was described by David B. Weishampel and Philip R. Bjork in 1989 . The only well @-@ accepted North American species of Iguanodon , I. lakotaensis was described from a partial skull from the Barremian @-@ age Lower Cretaceous Lakota Formation of South Dakota . Its assignment has been controversial . Some researchers suggest that it was more basal than I. bernissartensis , and related to Theiophytalia , but David Norman has suggested that it was a synonym of I. bernissartensis . Gregory S. Paul has since given the species its own genus , Dakotadon . 
