Aardonyx, a term derived from Afrikaans "aard" meaning "earth" and Greek "onux," signifying "nail" or "claw," belongs to the category of basal sauropodomorph dinosaurs. It is primarily associated with the type species Aardonyx celestae, which was unearthed in the Early Jurassic Elliot Formation of South Africa. The specific epithet, "celestae," honors Celeste Yates, who played a significant role in preparing a substantial portion of the initial fossil material related to this species.

Aardonyx exhibits arm features that lie somewhere between those of prosauropods and sauropods. Judging by the structure of its hind limbs and pelvic girdle, this dinosaur typically employed bipedal locomotion but could also transition to quadrupedal movement, akin to the behavior of Iguanodon. Notably, Aardonyx demonstrates a transitional shift towards the bulk-browsing feeding style characteristic of sauropods.

The jaws of Aardonyx are narrow and V-shaped with a pointed symphysis, a primitive trait shared with other basal sauropodomorphs. In contrast, sauropods possess broad, U-shaped jaws that facilitate a wider bite. The absence of a lateral ridge at the caudal end of the dentary suggests a lack of fleshy cheeks, which is viewed as an adaptation for a broader gape to aid in bulk browsing—a feature observed in nearly all sauropods.

Aardonyx's limb characteristics indicate a habitual bipedal stance, but attributes found in both the forelimbs and hindlimbs suggest a trend towards increased quadrupedalism. This trend ultimately led to the obligatory quadrupedal posture seen in sauropods. Aardonyx is a noteworthy sauropodomorph, serving as a representative example of the transitional phase between bipedal ancestors and their quadrupedal descendants. This transformation is particularly evident when examining the legs, which display adaptations for a slower yet more robust mode of walking. These alterations, coupled with a progressively quadrupedal approach to weight-bearing, paved the way for sauropods to attain truly enormous sizes.