Dinheirosaurus is not extremely well known, and as a consequence, its phylogenetic position is not certain. In 2012 during a redescription of the taxon by Philip Mannion et al., it was recovered, in both cladograms, to be sister species to Supersaurus vivianae and together forming the most basal diplodocines. A 2012 cladogram, published by Mannion et al. and using a modified matrix of Whitlock (2011) found that Dinheirosaurus was more primitive than Torneria and more derived than Apatosaurus. However, a cladogram from 2014 found that their group was supported, but in fact more primitive than Apatosaurus, and therefore outside Diplodocinae. In 2015, Dinheirosaurus lourinhanensis was considered a species of Supersaurus in a new combination S. lourinhanensis. Their results are shown below.