Aridal Formation
The Aridal Formation in the Sahara Desert of southwestern Morocco is a fossil formation with rocks dating to the Lutetian - Priabonian, preserving a middle Eocene shallow coastal environment.
The formation represents the world's richest Bartonian archaic whale assemblage, including protocetids and basilosaurids.
Paleobiota
Birds
Includes the earliest occurrence of the genus Pelagornis, extending its fossil record back by at least 10 million years.| Taxa | Rock Unit | Age | Image |
| Pelagornis sp. | Gueran | Bartonian | |
| Pelagornithidae indet. | El Breij Unit II | Bartonian |
Mammals
Alongside a rich assemblage of archaic whale taxa including two additional unnamed protocetid species, there are also possible remains of the earliest occurrence of Barytherium.| Taxa | Rock Unit | Age | Image |
| Pappocetus lugardi | Gueran, Sabkha of Lebreij | Bartonian | |
| Eocetus schweinfurthi | Gueran, El Breij Unit II, El Breij Unit III | Bartonian | |
| Chrysocetus fouadassii | Gueran | Bartonian | |
| Platyosphys aithai | Gueran | Bartonian | |
| ? Barytherium sp. | Gueran | Bartonian |
Reptiles
There are at least three indeterminate species of turtles: two marine cryptodires, a cheloniid, a dermochelyid, and a possible littoral pleurodire. Two species of longirostrine crocodylians are present, including a gavialoid similar to Eogavialis africanum, and one too fragmentary to identify beyond being a crocodyliform.| Taxa | Rock Unit | Age | Image |
| Pterosphenus schweinfurthi | Gueran | Bartonian | |
| Palaeophis africanus | El Breij, Unit I | Lutetian | |
| Palaeophiidae indet. | Sabkha of Lebreij | Bartonian | |
| Cordichelys antiqua | El Breij, Unit I | Lutetian | |
| Cheloniidae indet. | Gueran | Bartonian | |
| Dermochelyidae indet. | Gueran | Bartonian | |
| Pleurodira indet. | Gueran | Bartonian | |
| Gavialoidea indet. | Gueran | Bartonian | |
| Crocodyliformes indet. | Gueran | Bartonian | |
| Crocodylia indet. | El Breij Unit I, Sabkha of Lebreij | Lutetian Bartonian |