A NEW LAGOMORPH FROM THE LATE MIOCENE OF CHAD (CENTRAL AFRICA)

Abstract

A new species of the genus Serengetilagus, here named S. tchadensis n. sp., is described from Toros Menalla deposits, Late Miocene of Djurab Erg (North Chad, central Africa). It shows primitive features, such as a simple archaeolagine-type p3, with only two main external folds, and upper cheek teeth strongly widened with wear. Its size and skeletal features resemble S. praecapensis from the Middle Pliocene of Laetoli (Tanzania). They differ in several cranial and dental features (choanae width, zygoma, orbits, basicranial-basifacial angle, lack of hypoflexus in P2, short and asymmetric hypoflexus in P3-M2, lack of lingual folds in p3, etc). Individual variations in S. tchadensis n. sp. approach S. praecapensis. The genus Serengetilagus is here assigned to the subfamily Archaeolaginae  and related to Hypolagus, namely to H. gromovi  from the Late Miocene of Southern Russia. Other related species are Serengetilagus orientieuropaeus and primitive species of the genus Trischizolagus, such as T. maritsae and T. crusafonti. Pliocene leporids from Spain, Ukraine, Russia, Afghanistan and Mongolia have been questionably attributed to Serengetilagus or Trischizolagus. Several features are here proposed to distinguish both genera.
Serengetilagus could have a mixed fossorial-cursorial mode of life, as can be inferred by its ecomorphological traits (combining features of hare and rabbit) and taphonomical indications. This new African archaeolagine is contemporaneous of the widespread palaeolagine Alilepus, recorded in the Late Miocene of Kenya. The independence of these two lineages is favoured after revision of previous hypotheses on the phylogeny of the highly diverse Mio-Pliocene peri-Tethysian leporid species.