[2] This taxon is also noteworthy because diplodocoid sauropods had the highest tooth replacement rates of any vertebrates, as exemplified by Nigersaurus, which had new teeth erupting every 30 days.

In 2005, Mike P. Taylor and Darren Naish reviewed diplodocoid phylogeny and taxonomy, and realized that Diplodocimorpha could not be synonymized with Diplodocoidea.

The authors carried out a phylogenetic analysis and noted that Suuwassea, although more derived than Rebbachisauridae, is in a trichotomy with other families belonging to Diplodocoidea (Diplodocidae and Dicraeosauridae).

Flagellicaudata was defined as a node-based clade consisting of the most recent common ancestor of Dicraeosaurus and Diplodocus and all of its descendants.

[7] Haplocanthosaurus priscus Zapalasaurus bonapartei Cathartesaura anaerobica Limaysaurus tessonei Nigersaurus taqueti Demandasaurus darwini Dyslocosaurus polyonychius Suuwassea emilieae Dystrophaeus viaemalae Brachytrachelopan mesai Tharosaurus indicus Amargasaurus cazaui Dicraeosaurus hansemanni Amphicoelias altus ?Apatosaurinae gen. et sp.