Nigersaurus

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

Overview: Nigersaurus was a highly unusual sauropod dinosaur. For starters, it doesn’t fit with the general stereotype of sauropods being enormous, only having been maybe nine meters long and a few tons in weight. This actually isn’t too unusual, as even derived sauropods tended to vary widely in size. What was really unusual was its skull and jaws. The creature’s snout was wide and squared-off at the front, lined by a large number of tiny, tightly-packed teeth. Jaw shape, of course, tends to differ among animals in accordance with their diets and lifestyles, so a wide muzzle in and of itself wasn’t too strange. What sets Nigersaurus apart was how its jaws were modified as it evolved toward this form. Instead of the front of its snout widening, the sides of its jaws actually rotated forward. Its teeth, which could number in the hundreds, formed a straight cutting surface and appear to have constantly replaced themselves throughout its life. Overall, Nigersaurus had a very lightly constructed and fragile skull, even for a sauropod.

There is some debate as to why Nigersaurus evolved such unique jaws, but most see it as a highly specialized low-browser. Most sauropods were mid to high-browsing herbivores, using their long necks to feed from tall conifers and other trees, but Nigersaurus went in the opposite direction. In some studies, it has been found that Nigersaurus may’ve habitually held its head low towards the ground, though to what extent this is true is debated. Nigersaurus belonged to a family called the Rebbachisauridae, which mainly contained other odd, low-browsing and mostly small to medium-sized sauropods. These animals belonged to the larger superfamily Diplodocoidea, so they were distantly related to famous diplodocid sauropods like Diplodocus and Apatosaurus. Described in 1999, Nigersaurus takes its name from the nation of Niger, where it was found, in what is today a desert but was once a far more humid environment. It’s known from Niger’s Elrhaz Formation, so it lived during the Early Cretaceous, alongside dinosaurs like Ouranosaurus and Suchomimus.