The Fayyum is a region and an important fossil Lagerstätte in northern Egypt. The region comprises the Fayyum Basin, which is intensively used for agriculture, and adjoining areas; the important areas of discovery are mostly north and west of Lake Qarun. The Wadi al-Hitan, known for its numerous whale fossils and since 2005 UNESCO World Natural Heritage Site, forms the south-western end. The deposits of the Fayyum belong to various geological formations. They are mainly composed of limestone, siltstone and sandstone. The lower sections consist of marine sediments, while the upper, continental sediments were formed in a coastal landscape. The formation period ranges from the Middle to the Upper Eocene to the Lower Oligocene, which corresponds to an age of around 41 to 28 million years ago. The entire sedimentary complex is overlain by basalt, which dates back to volcanic activity around 24 million years ago.
The very rich fossil evidence of the Fayyum includes plants, invertebrates and vertebrates, and numerous trace fossils have also survived. Vertebrates include fish, reptiles, birds and mammals. Some forms represent important evolutionary links in the development of individual lineages, particularly in the sloths, proboscideans, manatees and cetaceans. Among the fossil primates are early forms of Old World monkeys. In addition, marsupials, tenrec-like, even-toed ungulates, bats and rodents also occur. Some groups such as the giant herbivorous Embrithopoda or the predatory Hyaenodonta or the insectivorous Ptolemaiida have no descendants living today. Due to this diversity, the Fayyum is the most important fossil site of the African Paleogene. On the basis of the terrestrial vertebrates, a delta-like landscape crisscrossed by watercourses can be distinguished. landscape near the sea coast under tropical climate conditions can be reconstructed.
The first fossil finds in the Fayyum date back to the middle of the 19th century. A major phase of investigation took place at the transition from the 19th to the 20th century, when English, American, German and French researchers were active on site at times. During this time, numerous fossils were recovered; this led to some important discoveries that contributed to the supra-regional fame of the Fayyum region. In addition, the first investigations into geology were also carried out. Modern research began in the 1960s and continues to this day. It is organized internationally. Analyses of the finds lead to the description of new fossil forms from the Fayyum almost every year.