Abstract
Island biotas have disproportionately influenced the history and development of evolutionary
biology, but understanding their genesis and evolution across geological timescales has
been hindered by a poor fossil record. Here we augment the insular Eocene (~43 Ma) mammalian
fauna known from the Pontide terrane of central Anatolia by describing two new
metatherian taxa (stem marsupials) from the Lu¨ lu¨k Member of the Uzunc¸arşıdere Formation
in the Orhaniye Basin. Geological and paleontological data indicate that the Pontide terrane
was an island on the northern margin of Neotethys during the middle Eocene. Reflecting its
geodynamic context in a region of active tectonic convergence, the Eocene Pontide terrane
hosted a unique combination of Laurasian and Gondwanan mammals, including an anachronistic
radiation of pleuraspidotheriids (archaic ungulates) that went extinct on the European
mainland ~13 Ma earlier. Most of the mammalian clades occupying the Pontide terrane colonized
it by dispersal across marine barriers rather than being stranded there through vicariance.
Endemic radiations of pleuraspidotheriid ungulates and polydolopimorphian
metatherians on the Pontide terrane reveal that in situ diversification was an important factor
contributing to faunal assembly and evolution. The insular fauna that arose on the Pontide
terrane is highly analogous to that of modern Sulawesi, which evolved under strikingly similar
geological conditions. Illustrating the ephemeral nature of insular biotas across macroevolutionary
timescales, the demise of the Pontide fauna coincided with paleogeographic changes
enabling more cosmopolitan taxa to reach it for the first time. The high level of endemism
shown by the mammalian fauna of the Uzunc¸arşıdere Formation eliminates the Pontide terrane
as a potential early Eocene dispersal corridor between western Europe and India.
Citation
Me´tais G, Coster PM, Kappelman JR,
Licht A, Ocakoğlu F, Taylor MH, et al. (2018)
Eocene metatherians from Anatolia illuminate the
assembly of an island fauna during Deep Time.
PLoS ONE 13(11): e0206181. https://doi.org/
10.1371/journal.pone.0206181