Definition adopted: The most inclusive clade that includes Iguanodon bernissartensis but neither Megalosaurus bucklandii nor Diplodocus carnegii (after Baron et al., 2017a).

Characters in support: Horizontal or only gently arched premaxillary palate (Char. 17: 0 → 1); strongly curved and hook-shaped jugal process of the ectopterygoid (Char. 57: 0 → 1; Fig. 5E); ventrally inclined dorsal surface of the rostrum of the dentary (Char. 74: 0 → 1); retroarticular is slightly upturned at its distal end (Char. 82: 0 → 1; Fig. 7F); premaxilla with four teeth (Char. 84: 0 → 1); teeth ankylosed into the alveoli (Char. 100: 0 → 1; Fig. 7G); and medial articular facet of the proximal portion of the femur is straight in caudomedial view (Char. 213: 0 → 1; Fig. 7J).