The age of the formation has been subject to debate, but the most recent research indicates that it covers both the latest parts of the Eocene and the Early Oligocene, spanning over the boundary between these two time periods.

Research suggests that the Jebel Qatrani Formation featured a mix of subtropical to tropical forest, lowland swamps and marshes, ponds and rivers that would empty northward into the Tethys Sea.

This is supported by the presence of water-dependent fauna including podocnemidid turtles, crocodilians, sea cows, various fish, jacanas, early flamingo-relatives, ospreys, herons and shoebills.

Primates are represented by over a dozen genera, several forms of early elephants have been recovered from the sediments including the terrestrial Phiomia and the semi-aquatic Moeritherium.

During this time the region was studied extensively by scientists including but not limited to Charles William Andrews, Henry Fairfield Osborn, René Fourtau and Ernst Stromer.

Radioisotopic dating was conducted on the overlying Widan el Faras Basalt, however the results of this suggested an age of 23.6 million years for its lower units, much younger than prior estimates for the Jebel Qatrani Formation.

However, in a 2006 publication Seiffert draws a comparison between the Fayum fauna and the fossil record of the Ashawq Formation in Oman, which notably preserved vertebrates as well as foraminifera useful in dating.

Assuming the traditional interpretation of the Jebel Qatrani Formation, this would mean that many of these taxa would have had to appear 2 to 4 million years earlier in Egypt than in Oman, which is considered to be unlikely by Seiffert.

Although lithology suggests that most fossils were deposited on sandbanks after being transported by currents, the authors argue that swamps could have easily formed along the banks of the river that was present during the Oligocene and may account for the mudstone found in certain quarries.

[4] In a 2001 paper Rasmussen et al. argued that the sandstone and mudstone of the formation likely formed as sediments were aggraded by a system of river channels that emptied towards the west into the Tethys.

[5] Overall this indicates that this region was a part of an extensive belt of tropical forest that stretched across what is now northern Africa, which would gradually give rise to open woodland and even steppe the further one was to travel inland.

[30] Hyracoidea Bunohyrax Geniohyus[2] Megalohyrax[45] Saghatherium[42] Thyrohyrax Titanohyrax[45] Marsupalia Rodentia Acritophiomys[48][49][33] Gaudeamus[48][2][49][51][33] Metaphiomys[2][49] Phiomys[2][49] Pholidota Ptolemaiida Cleopatrodon[54][55] Ptolemaia[55] Primates Apidium[57][2] Propliopithecus[57][3][2] Qatrania[58][61][2][57] Proboscidea Palaeomastodon[2] Sirenia