The genus Acer from the lower/middle Pleistocene Sisian Formation, Syunik region, South Armenia

The diversity of Acer foliage and fruits (798 specimens) of the fossil-rich diatomitic sediments of the Sisian Formation in the Vorotan River Basin, Syunik region, southern Armenia, has been investigated. Based on foliage and fruitlets Acer cf. cappadocicum Gleditsch, A. cf. heldreichii Orphanides ex Boissier ssp. trautvetteri (Medwedev) Murray, A. cf. hyrcanum Fischer & C.A. Meyer, A. cf. ibericum Bieberstein and A. cf. platanoides L. were identified. Acer cf. opalus Miller ssp. obtusatum (Willdenow) Gams has been identified based on one leaf fragment only, Acer sp. cf. sosnowskyi Doluchanov and A. cf. velutinum Boissier based on fruitlets. Further species are Acer subcampestre Göppert (leaves) and Acer campestrianum Dorofeev (fruits). Seed-bearing fruit parts and bud scales are numerous. They have been identified at the genus and, in some cases, to the species level. The fossil record is compared to the modern maple species of the Caucasus region. The results clearly show a higher diversity and wider distribution of modern maples in this region during the early-middle Pleistocene.