The Aridal Formation in the Sahara Desert of southwestern Morocco is a fossil formation with rocks dating to the Lutetian - Priabonian (47.8 - 33.9 million years ago), preserving a middle Eocene shallow coastal environment.

The formation represents the world's richest Bartonian archaic whale assemblage, including protocetids and basilosaurids.

Includes the earliest occurrence of the genus Pelagornis, extending its fossil record back by at least 10 million years.

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.

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 (which is typically known from younger strata), and one too fragmentary to identify beyond being a crocodyliform.