Nigersaurus (meaning "Niger Lizard") is a genus of diplodocoid sauropod dinosaur from the middle Cretaceous period, about 119 to 99 million years ago during the Aptian or Albian age. This dinosaur was described by Paul Sereno and colleagues in 1999. It is one of the most common genera found in the rich fossil vertebrate fauna of the Elrhaz Formation, Gadoufaoua, in the Niger Republic, discovered by Philippe Taquet, and described in a paper published in 1976.
Nigersaurus was a plant-eater that had an unusual mouth "shaped like the wide intake slot of a vacuum" that took in food and chewed it with over a hundred very small, sharp teeth. Previously, such tooth batteries have been known only in hadrosaur and ceratopsian dinosaurs, but the discovery of Nigersaurus showed that at least one sauropod lineage, the rebbachisaurids, had them, as well.
Although a common genus, Nigersaurus had been poorly known until 2005, because of the delicate and highly pneumatic (filled with air spaces) construction of the skull and skeleton, which means that the fossil remains have been disarticulated. Sereno and Jeffrey A. Wilson in 2005 provided the first description of the skull and feeding adaptations. Nigersaurus had as many as 500 or 600 teeth in its shovel-shaped head. In 2007 an article published in the Public Library of Science by Sereno et al. detailed the unique anatomy of Nigersaurus. Study of its inner ear shows that Nigersaurus head was oriented downwards and was best suited for low level browsing.