Assignment of Acanthopholis horridus to the Nodosauridae is based primarily on tooth structure and presence of tall conical spines and keeled plates that are or slightly convex medially.

Acanthopholis horridus is based on remains that may or may not pertain to a single individual/species. There is a lot of referred material that does not obviously belong to this taxon. It is certainly nodosaur, unlike the taxa discussed below, which though probably nodosaur, show no synapomorphies of that group.

Acanthopholis/Syngonosaurus macrocercus contains both ankylosaur scutes and ornithopod vertebrae, as well as material that can only be termed Dinosauria indet. and some that is lost.

Acanthopholis platypus is based on a sauropod metatarsus and ankylosaur caudal centra and a phalanx.

Acanthopholis stereocercus includes ornithopod dorsal vertebrae and ankylosaur caudal vertebrae and dermal spine.

Acanthopholis "hughesii" [Nomen Nudum] (Pereda-Suberbiola & Barrett, 1998) (SMC B55463-55490) six dorsals, seven caudals, transverse process, four metapodials, three phalanges, seven dermal plates All are ankylosaur except some of the metapodials (Dinosauria indet.) and some dorsal vertebrae (Ornithopoda indet.).

Acanthopholis "keepingi" [Nomen Nudum] (Pereda-Suberbiola & Barrett, 1998) (SMC B55491-55526) five dorsals, six caudals, three transverse processes, rib, two chevrons, metatarsal, two phalanges, fragmentary ilium(?), thirteen dermal plates, two undetermined bones All are ankylosaur except some dorsal and caudal vertebrae (Ornithopoda indet.), a limb fragment (turtle) and the chevrons, rib, metatarsal and phalanges (Dinosauria indet.).