Galton (1990) used Massospondylidae as a monospecific taxon for Massospondylus carinatus. Sereno (1998) defined the taxon as stem-based to include the well known prosauropod Massospondylus carinatus and any other prosauropods closer to it than to Plateosaurus engelhardti.

Basal saurropodomorph relationships are poorly resolved by all recent studies (Sereno 1999, Yates 2003, Yates and Kitching 2003) largely because of the uniformity of their osteology. Despite this flux in theirr relationships, ther eis usually a taxon of low-skulled basal sauropodomorphs allied with Massospondylus carinatus that usually includes Lufengosaurus hunei and sometimes Yunnanosaurus huangi. This may constitute the only subclade of basal sauropodomorphs that is possible to consistently link together in phylogenetic analyses.

The active definition is a first-order revision of the initial definition in Sereno (1998). Including Saltasaurus loricatus as an external specifier ensures that only the closest relatives of Massospondylus carinatus will be included, and does not depend on the monophyly of most or all prosauropods.