Fayyum (fossil deposit)

About 5 km further northeast towards the Fayyum basin, another group of hills extends, among them the Garet Gehannam rises about 120 m above the surrounding area as an important landmark.

In the outcrops to the north of Lake Qarun, they appear as a uniform sedimentary complex, which fans out to the west towards the Wadi el-Hitan and interlocks with the Gehannam Formation in its lower and middle sections.

At the bottom is the Umm Rigl Member with a 30 to 65 m thick sequence of sandy, partly bioclastic, hard limestones, which alternate with gypsum and calcareous, finely layered clay and siltstones.

Later, the construction of an 8 km long dam at el-Lahun and the creation of further fresh water basins in the south-east of the Fayyum area were added.

Also worth mentioning are some requiem sharks such as Carcharhinus and Misrichthys, which form a certain freshwater component and occur in comparatively larger numbers in the upper sections of the Maadi Group.

[32][33][34] In general, marine elements recede into the background in the upper sections of the Maadi Group from the Qasr-el-Sagha Formation onwards and freshwater or brackish water fish are increasingly found.

[52] However, Eogavialis proved to be very basal in the evolution of the gavials, possibly belonging to a lineage even before the split into today's Southeast Asian and the extinct South American forms.

[77] Other early forms are Geniohyus, Bunohyrax or Pachyhyrax, often differing only in the modifications of the grinding teeth from a humped (bunodont) chewing surface pattern to one with a crescent-shaped shearing ridge (selenodont).

Its very early branching within the manatees is still recognizable, among other things, by the clearly developed fore and hind extremities and the strong spinous processes of the thoracic vertebrae, which probably allowed a semi-aquatic life.

Based on stomach remains of Basilosaurus from the Wadi el-Hitan, it could be shown that the giant toothed whale hunted its smaller relative Dorudon and probably preferred to prey on its offspring.

[30] Dorudon, on the other hand, probably fed mainly on fish and used the then shallow sea waters to give birth to its offspring, as individual finds of young animals suggest.

[93] Stromerius and Masracetus appear rather rarely; individual teeth and parts of the body skeleton of the latter were found in the Gehannam Formation north of Lake Qarun.

While there are only a few finds of Qatraniodon and Nabotherium each, the fossil material of Bothriogenys consists of more than 2,000 tooth and bone elements as well as individual complete skulls of animals of all ages.

Plesiopithecus, defined on the basis of a lower jaw and later supplemented by additional finds such as a partial skull,[121][122] in turn joins the continental predecessor forms of the fingered animal of Madagascar.

[125] Masradapis, which weighed around 900 g, may in turn have consumed a higher proportion of seeds and fruit due to its larger posterior molars and stronger lower jaw.

Based on the few teeth and skull remains found so far, an animal weighing just over 200 g can be reconstructed, which, unlike most modern apes, led a nocturnal lifestyle.

However, a single lower jaw of a probably dwarfed, but not yet precisely determined oligopithecid was found in a significantly higher position (locality M) and possibly represents one of the last records of this primate group.

As early as the end of the 19th century, the fossils of the Fayyum were classified according to biostratigraphic considerations, for example in the composition of the shark fauna, a classification into the Upper Eocene and the Lower Oligocene was assumed.

The position of the Gebel-Qatrani Formation proved to be particularly problematic, which, depending on the study, belonged either entirely to the Upper Eocene or the Lower Oligocene or dated to the transition between the two time periods.

Measurements carried out in the 1990s in the same areas, combined with a review of the previously obtained age estimates, confirmed the Upper Oligocene position for the basalt; the new values amounted to around 23.6 million years.

As a result of the work, it could therefore be assumed that the Fayyum series of deposits belonged almost entirely to the Eocene, with only the uppermost section of the Gebel-Qatrani Formation falling within the transition to the Lower Oligocene.

[149] Later analyses recorded a far more extensive sediment sequence starting in the basal areas of the Qasr-el-Sagha Formation and also carried out a comparison with other sites in the immediate and wider surroundings.

[156] The Lower to Middle Eocene site complex Gour Lazib, western Algeria, plays a stronger mediating role, as forms already occur here with Megalohyrax and Titanohyrax, which are also known from Fayyum.

Older localities such as Adrar Mgorn and N'Tagourt yielded primitive insectivorous mammals such as Afrodon or Todralestes, which possibly correspond to an African-endemic fauna.

The fossils found in the Guerrani Member of the Samlat Formation consist of numerous fish remains as well as turtles, crocodiles, isolated birds and marine and terrestrial mammals.

[179][180] From the Arabian Peninsula, the Thaytiniti and Taqah sites in Oman can also be mentioned, which contain a fauna roughly contemporary with the upper sections of Fayyum.

[15] The first fossil finds of modern times go back to Arthur Bedford Orlebar (1810–1866), who in 1845 found some sintered tree stumps up to 20 m long in sandstone layers.

[1] A year later, Andrews published a comprehensive catalog of the vertebrate finds under the title A descriptive catalogue of the Tertiary Vertebrata of the Fayum, Egypt, which is still one of the standard works on the Fayyum fossils today.

Osborn himself only stayed in Egypt for the beginning of the expedition, but he made a short detour to the Wadi el-Hitan, which he named Zeuglodon valley according to Beadnell.

[22][15] Independently of the previous investigations, the National Museum of Natural History of Paris, under the organizational leadership of Marcellin Boule and Jean Albert Gaudry, carried out a two-week expedition to the Fayyum in March/April 1904, which was financially supported by Edmond de Rothschild.