In 2005, Allain established some distinctive traits. "Dubreuillosaurus" has an unusually low and long skull, with a length three times the height. In the upper corner of the front edge of the nasal branch of the maxilla, a kink is present, separating a convex curvature below from a concave curvature above. The descending branch of the postorbital has a U-shaped cross-section. The parietal bones are not visible in side view. The supratemporal fenestra has a straight inner edge. A paraquadratic fenestra is lacking. A well-developed process is present on the underside of the jugal branch of the ectopterygoid. The rear edge of the jugal branch of the ectopterygoid, in front of the infratemporal fenestra, is deeply grooved. The lower jaw has a large external mandibular fenestra. The "foramen mylohyoideum" is largely oriented to the front and below. The head of the thighbone is directed to the inside and below. The front underside of the thighbone has a concave surface. In 2012 Matthew Carrano added one autapomorphy: on the rear of the braincase there is a notch between the basioccipital and the bone surface formed by the exoccipitals and the opisthotic.