Demandasaurus

Phylogeny: Dinosauria > Saurischia > Sauropodomorpha > Plateosauria > Massopoda > Sauropodiformes > Sauropoda > Gravisauria > Eusauropoda > Neosauropoda > Diplodocoidea > Rebbachisauridae > Rebbachisaurinae

Overview: Growing to be about twelve meters in length, Demandasaurus was medium-sized by the standards of the Sauropoda overall, but quite average for those in the rebbachisaurid family. Those dinosaurs belonging to this group were distinguished by a few noteworthy traits, foremost being their tall neural spines along most of their backs. In life, these spines probably supported a ridge of fat, muscle or other such tissue. We can observe these spines on Demandasaurus itself, specifically on those preserved on some of its upper tail vertebrae. Some other referred fossils of the animal are its femur, part of the pelvis, some ribs, and a few other vertebrae from the spine and neck. Parts of the snout, specifically the tip, are also known. These fossils paint it as a typical rebbachisaurid, but with a notably rounded snout profile, especially when compared to that of the related Nigersaurus, which had far more specialized jaws.

Rebbachisaurids often coexisted with other sauropods, likely occupying different niches. With very few exceptions, they were usually not the largest in their environments, so they fed mainly on low to mid-level vegetation. This included conifers, cycads, and similar plants. Demandasaurus itself is believed to have coexisted with the sauropod Europatitan, which was considerably larger and a part of the lineage that gave rise to the titanosaurs (though not a titanosaur itself). Fossils of both are known from the Castrillo de la Reina Formation, in what is today the north of Spain. Studies of the formation date it to the Early Cretaceous, or around one hundred and twenty-five million years ago. Other dinosaurs from the formation included iguanodontian ornithopods and some spinosaurids. Demandasaurus takes its name from Spain’s Demanda mountain range.