A new Late Miocene small vertebrate assemblage from the Ouarzazate Basin (High Atlas, Morocco) and its biochronological and paleoenvironmental significance

The Ouarzazate Basin is located between the southern flank of the Central High Atlas and the Anti-Atlas mountains (in Morocco). The Neogene is primarily represented by the Aït Ouglif and Aït Kandoula alluvial formations, which are exposed in the Amekchoud section. Magnetostratigraphic data indicate a Middle to Late Miocene age for this sequence, from the upper Langhian to the Messinian.

Despite extensive sampling, significant paleontological results were only obtained at level PAM 207, situated 773 m above the base of the Aït Kandoula formation. This level, characterized by reversed polarity, yielded a microvertebrate assemblage preliminarily described by Tesón et al. (2010). In this work we present a revised study of the small vertebrates from PAM 207, providing updated information on its faunal composition as well as new insights into the biostratigraphy and paleoenvironment of the locality.

The assemblage includes fishes, amphibians, reptiles, insectivores, and rodents. Based on the rodent association, PAM 207 is slightly younger than Guefait 1 (Morocco) and close in age to Sidi Salem (Algeria), representing one of the oldest early Turolian localities in North Africa. It postdates Tafna 2 (9.1–8.7 Ma) and predates Amama 2 (7.7 Ma), supporting its correlation with chron C 4 r (8.77–8.12 Ma).

Paleoenvironmental evidence suggests temperate freshwater habitats within an open landscape with a certain degree of vegetative cover, under relatively arid conditions. Overall, PAM 207 provides new evidence that contributes to the establishment of a chronologically constrained Late Miocene biochronological scheme for North Africa and enhances our understanding of paleoenvironments during this interval.