Alocodon was originally referred to as a member of the
ornithopod family
Fabrosauridae by Thulborn in 1973, closest to
Fabrosaurus but also related to
Echinodon and
Trimucrodon. Galton then suggested in
1983 that
Alocodon was related to
Othnielia, based on similarities of the teeth, placed within the ornithopod family
Hypsilophodontidae. Given that the species was only represented by teeth,
Alocodon was designated as a
nomen dubium in
1990 by
David B. Weishampel and
Lawrence M. Witmer, as an indeterminate member of
Ornithischia outside Ornithopoda. While a basal ornithischian position outside Ornithopoda was retained by
Paul Sereno in
1991, it was considered a possibly valid taxon based on its broad central denticle. José Ruiz-Omeñaca reclassified
Alocodon in
1999, based on a reconsideration of features and classifications specified previously. Though it had similarities to ornithopod, Ruiz-Omeñaca instead placed it within
Thyreophora as an intermediate taxon, as the tooth crown was asymmetrical, with the cingulum on one side higher than the other, and no ridges present on the crown. Weishampel, Witmer and colleague
David B. Norman followed their 1990 opinion on
Alocodon in
2004, though they noted that further study could potentially support the validity of the taxon. Features of the teeth identified by José I. Canudo and colleagues in 2004 instead supported a more specific position for
Alocodon, as a member of
Ankylosauria. Canudo
et al. based this assignment on the anatomy of the denticles and
cingulum of the crown. A denticulate cingulum present in
Alocodon was also identified as an ankylosaur feature, by Paul M. Barrett and colleagues in
2010, though more material was considered necessary to verify the importance of the feature.
Alocodon was considered an ornithopod by Filippo M. Rotatori and colleagues in
2020. Most recently, a comprehensive analysis of early ornithischian evolution found
Alocodon to exhibit traits representative of
Parapredentata, but could not narrow down its classification further. == Paleoecology ==