The Topernawi area of west Turkana, northern Kenya, preserves a number of recently discovered vertebrate fossil localities of mid-Oligocene age. The Topernawi fauna provides important new data on mammalian evolution in equatorial eastern Africa during the mid-Cenozoic. Here, we describe five new species of hyracoids from Topernawi: Nengohyrax josephi, Abdahyrax philipi, Geniohyus ewoii, Thyrohyrax lokutani, and Thyrohyrax ekaii. These species range in reconstructed body mass from ∼8 to ∼150 kg, comparable to the body size range that has been observed at other hyracoid-rich Paleogene sites. We use Bayesian tip-dating phylogenetic analyses to estimate hyracoid relationships. We find that non-Thyrohyrax species from Topernawi are members of Geniohyidae, a clade of bunodont, Paleogene hyracoids. Despite being approximately the same age as some of the youngest and best-sampled horizons in the Jebel Qatrani Formation (Fayum, northern Egypt), the Topernawi hyracoid fauna is distinct, and shows no overlap at the species level; it also shows no species overlap with the ∼1.5–2.5 Ma younger Chilga localities in northern Ethiopia. The hyracoid assemblage from Topernawi adds to a growing body of evidence which suggests that certain distinctive clades known from earlier Oligocene horizons in northern Africa (Saghatherium, Selenohyrax, Titanohyrax) did not persist into the late Oligocene.
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4 November 2024
Hyracoidea from the Oligocene of Topernawi, Turkana Basin, Kenya
Natasha S. Vitek,
Erik R. Seiffert,
Steven Heritage,
Margaret Wambui Gaiku,
Craig S. Feibel,
Francis J. Sousa,
Isaiah O. Nengo,
Eipa Emmanuel Aoron,
Patricia M. Princehouse
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