New material of the frog Hungarobatrachus szukacsi Szentesi & Venczel, 2010, from the Santonian of Hungary, supports its neobatrachian affinities and reveals a Gondwanan influence on the European Late Cretaceous anuran fauna

Abstract

The Late Cretaceous anuran Hungarobatrachus szukacsiSzentesi & Venczel, 2010 was erected for isolated ilia and tibio-fibulae from the Santonian-age Iharkút locality, in northwestern Hungary. On the strength of ilial features, H. szukacsi was interpreted as a neobatrachian and possible ranoid, making it the only pre-Cenozoic occurrence for both clades in Laurasia. New ilia and the first examples of skull bones (incomplete frontoparietals, squamosals, maxillae, and angulosplenials) from the type locality provide new insights into the taxonomic distinctiveness, osteology, and evolutionary history of H. szukacsi. In addition to its diagnostic ilia (e.g., dorsal crest tall and ornamented laterally with prominent ridges; extensive interiliac tubercle developed across entire medial surface of acetabular region), H. szukacsi is characterized further by having a moderately hyperossified skull exhibiting such traits as frontoparietals, squamosals, and maxillae externally covered with prominent pit-and-ridge and weakly developed tuberculate ornament (i.e., exostosis), frontoparietals solidly fused along midline, frontoparietals expanded posterolaterally to form a broad squamosal process, squamosals expanded anteroposteriorly to form a plate-like lamella alaris, and maxilla articulating posteriorly with the quadratojugal to form a solid bony ‘cheek'. The first cladistic analysis to include H. szukacsi corroborates its neobatrachian status, but consistently places it among hyloids, rather than ranoids as originally proposed. Indications of hyloids on the African continent and in Madagascar during the Late Cretaceous, suggest that the ancestor of H. szukacsi may have dispersed from Africa, across the proto-Mediterranean and into Europe, prior to the Santonian.