The last occurence of Latonia (Anura: Discoglossidae) and the early Pleistocene herpetofauna of Pietrafitta (Central Italy).

The well-known fossiliferous lignite quarry of Pietrafitta (Umbria, Central Italy) yielded an abundant vertebrate assemblage that has been referred to the Farneta Faunistic Unit (Late Villafranchian, Early Pleistocene). The lignite lithosomes are a good example of plant matter accumulated in situ, over a relatively extended period of time, in a system of mashes at the periphery of a lacustrine intermontane basin. The occurence of fossil amphibians and reptiles has been quoted since 1977 by Ambrosetti & co-workers, while the chelonian fauna has been described by Kotsakis & Gregory in 1985. The recent analysis of all the material recovered so far allows to identify the presence of the following 2 amphibians and 4 reptiles: Latonia sp., Rana gr. R. ridibunda, Emys orbicularis, Colubrines indet., Natrix sp. and Vipera ammodytes. Anuran and snakes fragments devoid of taxonomical value probably belong to the above mentioned taxa. The amphibian remains outnumber those of the reptiles and, not considering the European pond terrapin, they represent nearly entirely the fossil herpetofauna. From a paleoecological point of view, although the taphonomical conditions of lignite deposit strongly bias the taxonomic composition of the fossil assemblage (it is unlikely that very small and delicate skeletons are preserved and recovered), the relative abundance of anurans and pond terrapins strengthens the presence of a humide environment with permanent water. All the fossil remains are isolated from the matrix and, with the exception of the chelonians whose shells are sometimes perfectly preserved, all the skeletal elements are completely disarticulated. A specimen of Latonia, although disarticulated, is represented by several elements found in a disordered group. The most important element of the Pietrafitta herpetofaunistic assemblage is represented by the large frog Latonia. According to a recent summary by Rage & Rocek, this genus seems to appear in the earliest Oligocene of France (MP 21), in the Miocene it is widespread from Spain to Russia, while in the Pliocene it is rather rare in Central Europe but still common in the Mediterranean area. It was thought to disappear at the end of the Pliocene but the Pietrafitta remains testify its survival into the Quaternary. The unquestionable presence of smooth maxillae contrast with the diagnosis of the only Pliocene species L. gigantea, and requires to reconsider the taxonomy of the genus or the specific chronological ranges.