Gadoufaoua, the Elrhaz beds

The name is Tuareg and it means the place where camels fear to go. That is the Tenere desert's assessment of the ground, and it is fair: Gadoufaoua today is very hot, very dry and very empty. It is also one of the great fossil graveyards on Earth.

The rock is the Elrhaz Formation, Early Cretaceous, roughly 125 to 112 million years old. At the time these sediments formed the country had trees, plants and wide rivers. Animals died, the rivers buried them, and as those rivers dried the remains stayed sealed for the next hundred million years.

The famous resident is Sarcosuchus imperator, the crocodyliform that the press named SuperCroc. Paul Sereno's teams recovered vertebrae, limb bones, armour plates and jaws from here, including a nearly complete skull six feet long, and published the animal in Science in 2001. It shares the formation with a striking cast. Nigersaurus taqueti, a rebbachisaurid sauropod, was first described from these beds in 1976 but only named in 1999, once better remains turned up; the species honours Philippe Taquet, who found it. Ouranosaurus nigeriensis, the sail-backed hadrosauriform, is known from two rather complete skeletons taken out of the Gadoufaoua deposits in 1965 and 1970, an animal seven to eight metres long weighing a couple of tonnes. The fish-eating theropod Suchomimus came from here too.

The science is still moving, and not always forward in a straight line. A recent phylogenetic reassessment of North African theropods concluded that the original hypodigms of two Elrhaz predators named by Sereno and Brusatte in 2008, Eocarcharia dinops and Kryptops palaios, are chimaerical, meaning each was built from bones belonging to more than one animal. Kryptops turns out to rest on an abelisaurid upper jaw combined with allosauroid material from elsewhere in the skeleton. The same analysis places Eocarcharia as the direct sister taxon to Suchomimus, and suggests closely related spinosaurid species living side by side is a recurring pattern rather than an error to be explained away.

This is a scientific site in a remote and difficult region, not a destination. What you take from it is the picture: rivers, trees and a crocodile with a six-foot skull, where now there is sand.