The Libycosaurus (Hippopotamoidea, Artiodactyla) intercontinental dispersal event at the early late Miocene revealed by new fossil remains from Kasserine area, Tunisia

ABSTRACT

Anthracotheres dispersed from Asia toward Africa at least three times: at the Eocene/Oligocene transition, during the early Miocene and later during the Miocene. Those dispersals are important datum events for African Tertiary biochronology. New fossil remains of early Libycosaurus, the genus implicated in the late Miocene dispersal, are described from a new Tunisian locality of the Kasserine area. The new fossils enhance the hypodigm of Libycosaurus algeriensis and increase the resolution of the phylogenetic position of this species using cladistics analysis. The inclusion of the genus Libycosaurus within the well-described Merycopotamus lineage allows us to constrain its dispersal time. Dispersal of this anthracothere from the Indian sub-continent to Africa was probably facilitated by sea level decrease during the early Tortonian, just preceding the Hipparion dispersal event. This new age estimation refines the resolution of the succession of late Miocene deposits in Maghreb and frames the date of the onset of the Sahara.

KEYWORDS:

• Cladistic analysis
• Bothriodontinae
• Merycopotamini
• Sahara
• Tortonian
• dispersal events

Acknowledgments

We would like to thank Baba El-Hadj Mallah, Clarisse Nekoulnang, and Mahamat Adoum (CNRD, N’Djaména, Chad), Michèle Morgan and John Barry (Peabody Museum of Harvard University, Cambridge, USA), Wilma Wessels (Utrecht University, Utrecht, Netherland), and Mohammed Mahboubi (Université d’Oran 2, Oran, Algeria) for granting us access to the collection in their care. We also acknowledge Suzanne Jiquel (ISEM) for sample preparation and casting. We thank the anonymous reviewers for their help to improve this manuscript. Fieldwork and post-field researches were supported by the French ANR-ERC PALASIAFRICA (ANR-08-JCJC-0017) and has also benefited from the French ANR program SPLASH (ANR-15-CE32-0010-01) and from grant of the Scientific Council of University of Montpellier.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This work was supported by the Agence Nationale de la Recherche [PALASIAFRICA (ANR-08-JCJC-0017), SPLASH (ANR-15-CE32-0010-01)]; Research Council of University of Montpellier.