[3] In November 1985, a partial skull and associated skeleton was brought to the attention of South Dakota School of Mines and Technology professor emeritus John Willard.

Coming from a hogback north of Sturgis, South Dakota, SDSM 8656 is from the Early Cretaceous Lakota Formation, but without better locality information its exact age was uncertain.

[5][6][7] American paleontologist Robert T. Bakker supported the distinction of I. lakotaensis in 1998, comparing it favorably to a skull previously described as part of Camptosaurus amplus as a more primitive species of Iguanodon.

[8] This other skull was named Theiophytalia in 2006 by American paleontologists Kathleen Brill and Kenneth Carpenter, who also found that the differences between I. lakotaensis and Iguanodon bernissartensis suggested that a new genus was needed.

[2] The importance of Dakotadon as the most complete Early Cretaceous dinosaur from the Black Hills region led Boyd and Pagnac to attempt to relocate the type locality to better determine its age and stratigraphy.

The complete holotype of Dakotadon after repreparation included a partial skull, lower jaws, and dorsal and caudal vertebrae, with some of the facial bones first described by Weishampel and Bjork either being missing or reidentified.