Lissamphibians from the late Eocene – early Oligocene transition of the Transylvanian Basin (Romania)

We report herein the fossil record of lissamphibians unearthed from the late Eocene – early Oligocene localities of the north-western side of the Transylvanian Basin. Among the late Eocene (Priabonian) fossil vertebrate sites, the Bociu locality yielded discoglossid and pelobatid frogs, while the Treznea locality yielded a moderately diverse assemblage of discoglossid (Latonia sp.), palaeobatrachid, pelobatid and ranid (Pelophylax sp.) frogs. The assemblages derived from the early Oligocene (Rupelian) fossil localities of Suceag 1 and Cetățuia Hill, Cluj-Napoca include salamandroid newts (Mioproteus gardneri), discoglossid (Latonia sp.), palaeobatrachid (Albionbatrachus oligocenicus) and ranid frogs (Pelophylax sp.). Disparity between the contemporaneous anuran assemblages from the Transylvanian Basin and those representing the more diverse cratonic Europe is derived mainly from the persisting insular conditions of the studied area. The drop of mean annual temperature in northern Europe and the enlarging freshwater corridors may have facilitated the southeastern distribution of highly aquatic amphibian groups like the proteid salamander Mioproteus, the ranid frog Pelophylax and the palaeobatrachid frog Albionbatrachus, the latter being considered a late Eocene survivor, recorded previously from the western part of the continent.