The great transgressions that occurred in the mid part of the Cretaceous have had a profound influence on the geology of many parts of the world. In North America, the seas flooded the central part of the continent to produce the Western Interior Seaway, while, in northern Europe, the incoming of the Chalk seas saw much of the continent disappearing below the waves. Across the northern part of Africa, the transgression was more gradual, but on a scale as large as that seen anywhere else. In the period preceding the great marine flooding, huge coastal plains developed across a vast tract of land that extends from what is now Niger to Egypt. These coastal plains were criss-crossed by great braided river systems and provided the perfect habitat for a huge range of fresh water and terrestrial animals.
Vertebrate fossils have been known from the coastal plain, fluvial rocks of the African Cretaceous for a long time; excavations in Egypt in 1912 recovered the remains of several species, including the unusual theropod, Spinosaurus. Subsequent expeditions to other areas of north and northwest Africa have yielded many additional species of dinosaurs, as well as a host of other fossils.
In the early 1990s, the southeastern part of Morocco was just starting to open up to tourism and, with it, the great geological wealth of the region was becoming better known. In addition to the rich and diverse fossil faunas from the sandstones and limestones of the Palaeozoic, fossils were starting to be discovered in the Cretaceous rocks that unconformably overlie the older successions. This unconformable sequence is most readily seen at Hassi Begaa situated about ten miles south Taouz, where it forms the great Kem Kem escarpment.