[2] Though it was originally described as having been found in an unnamed deposit in the Portuguese Leiria District of upper Callovian age,[1][3] it was identified as having come from the lower Oxfordian Cabaços Formation.

[3][4] 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.

[6] 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.

[7] 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.

[14] 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.