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The discovery of the AAS specimens widens the scope of knowledge on the Woodbine Formation ornithopods and corresponds well to previously discovered material; however, direct comparison with previously collected material is hampered by their fragmentary nature and lack of overlapping elements with the AAS specimen. The partial femur described by Lee (1997a), which was also found in the Lewisville Member, shares several features in common with the AAS femur (UTA-AASO-125) including a convex, laterally compressed greater trochanter, a cranial trochanter separated from the latter by a narrow groove, and a proximal origin for the fourth trochanter. This suggests that the femur (SMU 73062) and associated tibia and fibula may belong to the same taxon as the AAS specimen.

5.13. Reconstruction of AAS ornithopod using a generalized hadrosauroid skeleton as a model. Recovered fossils discussed in text are shaded gray. Artwork by Tracy Ford.

Because UTA-AASO-2003 is composed primarily of postcranial elements (Fig. 5.13) and Protohadros is based upon crania (Head, 1998), it is currently difficult to verify whether they represent independent taxa, or if the AAS specimen represents the postcranial skeleton of Protohadros. Both the AAS specimen and Protohadros are basal hadrosauroids of comparable grade. Although basal hadrosauroid taxa are widespread throughout the Cretaceous, most taxa do not overlap in time or space (Prieto-Márquez, 2010b). The AAS occurs in the Lewisville Member of the Woodbine Formation, whereas the type locality of Protohadros was reported by Head (1998) as occurring in the overlying, younger Arlington Member. However, the stratigraphic distribution of Protohadros is unknown, and the widespread presence of hadrosauroid material throughout the Lewisville and Arlington Members in the area suggests this material may all belong to the same taxon (i.e., Protohadros), which implies it was a widespread and common component of the Woodbine fauna during the early to middle Cenomanian. More cranial material and additional stratigraphic work are needed before this question can be sufficiently answered.