the back legs, as in most diplodocoids. Classification The remains of Nigersaurus were initially described by Taquet in 1976 as belonging to a dicraeosaurid, but in 1999 Sereno and colleagues reclassified it as a rebbachisaurid diplodocoid. These researchers speculated that since short necks and small size was known among basal diplodocoids, it may indicate these were ancestral features of the group. Rebbachisauridae is the basalmost family within the superfamily Diplodocoidea, which also contains the long-necked diplodocids and the short-necked dicraeosaurids. The eponymous subfamily Nigersaurinae, which includes Nigersaurus and closely related genera, was named by the American palaeontologist John A. Whitlock in 2011. The closely related genus Demandasaurus from Spain was described by the Spanish palaeontologist Fidel Torcida Fernández-Baldor and colleagues in 2011, and along with other animal groups that span the Cretaceous of Africa and Europe, this indicates that carbonate platforms connected these landmasses across the Tethys Sea. This was supported in 2013 by the Italian palaeontologist Federico Fanti and colleagues in their description of the nigersaurine Tataouinea from Tunisia, which was more related to the European form than to Nigersaurus, despite being from Africa, then part of the supercontinent Gondwana. Pneumatisation of the rebbachisaurid skeleton evolved progressively, culminating in the nigersaurines. Below is a cladogram following the 2013 analysis by Fanti and colleagues, which confirmed the placement of Nigersaurus as a basal nigersaurine rebbachisaurid. A 2015 cladistic study by Wilsona and the French palaeontologist Ronan Allain found Rebbachisaurus itself to group with the nigersaurines, and the authors suggested that Nigersaurinae was therefore a junior synonym of Rebbachisaurinae (since that name would have priority). The same year, Fanti and colleagues supported the use of Rebbachisaurinae over Nigersaurinae, and found Nigersaurus to be the basalmost member of this "Euro-African" subclade. In 2019, Mannion and colleagues pointed out that since Nigersaurus was found to be the sister taxon of all other nigersaurines in some studies, a Rebbachisaurinae clade may not necessarily include Nigersaurus itself (as well as the fact that the position of Rebbachisaurus could change in future analyses), and supported the continued use of the name Nigersaurinae over Rebbachisaurinae for all rebbachisaurids more closely related to Nigersaurus than to Limaysaurus. They found that nigersaurines were restricted to North Africa and Europe, and that Limaysaurinae was strictly known from Argentina. The same year, the Brazilian palaeontologist Rafael Matos Lindoso and colleagues used the name Nigersaurinae following Mannion's recommendation, and found Itapeuasaurus from