Theiophytalia is a genus of herbivorous iguanodontian dinosaur from the lower Cretaceous period (Aptian-Albian stage, about 112 million years ago[1]) of Colorado, USA.

[2] Detailed comparisons by Brill and Carpenter (2006) also showed that the skull differed in a number of key features from that of Camptosaurus, namely: a longer, heavier, and more rugose snout; a wider dorsal process on the maxilla; a proportionally smaller antorbital fenestra; and stouter quadrate, with a bulbous articulation for the lower jaw.

The specific name kerri honors James Hutchinson Kerr, who found the specimen.

[2] The article describing the find classified Theiophytalia as intermediate in derivation between Camptosaurus and Iguanodon.

[2] In 2010 and 2011 cladistic analyses of McDonald and colleagues, Theiophytalia has been recovered as a basal member of the Styracosterna and its closest relative was Hippodraco.