Frogs and toads in the holes: Late Miocene amphibians from the Gargano Terre Rosse fissures (Southern Italy)

Nowadays, Mediterranean islands are home to several, often endemic, amphibians. Knowledge is limited, however, about amphibian palaeocommunities in the islands and palaeoislands of the Mediterranean Sea, despite the certain presence of fossils in such areas. One case with known but understudied insular amphibian fossils are the Gargano Terre Rosse, a complex of fissures in Southern Italy representing the remaining evidence of a Late Miocene (palaeo)insular fauna. More than 20 years after their first mentions, we offer here detailed descriptions of the fossil amphibians from these fissures, identifying an unbalanced and poorly diversified amphibiofauna largely dominated by Latonia gr. seyfriedi and further composed by Hyla gr. arborea, aff. Bufotes gr. viridis, and Pelophylax sp. Notable is the absence of urodeles, reflecting a similar trend in modern Mediterranean islands. Based on preliminary data, it seems that the Terre Rosse amphibiofauna remained generally stable along the history of the palaeoisland, potentially thanks to the resilient and adaptable ecology of the identified taxa and/or a low competition in the insular palaeoenvironment. The absence of remains from the oldest biostratigraphic phase of the Terre Rosse assemblages and the taxonomic uncertainty of the identified anurans hinder any real proposal about the dispersal or areas of origin of these frogs and toads, but their morphology, including potential character mixture, decoupling from continental evolutionary trends in the respective groups, and appearance of unusual features, support them as part of palaeocommunities already affected by evolution in insular contexts.