A new palaeobatrachid frog from the early Oligocene of Suceag, Romania

The EoceneOligocene transition (Mammal Palaeogene zones, MP 2021) corresponds in Europe to a major faunal turnover, called the Grande Coupure' (= Great Break). This event, produced by worldwide cooling and regression of seas, reshaped the faunal composition of Europe and resulted in the extinction of numerous ectothermic taxa. We describe a new palaeobatrachid frog from the early Oligocene of Suceag 1 (Rupelian: MP 2324), Romania, and assign it to Albionbatrachus, a genus previously known only from the British Isles and thought to have gone extinct during the late Eocene (MP 20). Albionbatrachus oligocenicus sp. nov. is established on a distinctive frontoparietal bone, which differs from A. wightensis in a few details, including the morphology of the frontoparietal table and paraoccipital processes. The peculiar sculpture on the frontoparietal bears dense dermal vascularization, which might reflect adaptation to oxygen depleted environments. Two autapomorphic characters of the angulosplenial and ilium in A. oligocenicus sp. nov. likely reflect a shift in, respectively, feeding and locomotory behaviours. A phylogenetic analysis of the primarily Gondwanan group Xenoanura identifies Albionbatrachus as the sister taxon of Palaeobatrachus, and places these two genera as the sister group of a separate Pipidae + Avitabatrachus clade. The presence of A. oligocenicus sp. nov. in the Oligocene of Central Europe indicates that Albionbatrachus survived the Grande Coupure' and necessitates a revised palaeobiogeographical scenario for the genus. We propose that the geographical distribution of Albionbatrachus before the Grande Coupure' was wider, extending eastwards into Central Europe, and that the Grande Coupure' resulted in the extinction of Albionbatrachus only in the western part of its range. The final extinction of Albionbatrachus might have been associated with Oligocene climatic deterioration and with shrinking of specific aquatic habitats. http://zoobank.org/urn:lsid:zoobank.org:pub:AA35E61B-B563-4D89-9F47-08F61D2C4AC7