| Abstract | A discoglossid frog, Eodiscoglossus oxoniensis sp. nov. is described from the Upper Bathonian Forest Marble of Oxfordshire. It closely resembles Eodiscoglossus santonjae from the Jurassic-Cretaceous boundary of Spain but can be distinguished by characteristics of the ilium and premaxillary. The E. oxoniensis specimens represent the earliest European material critically identifiable as the frog and the earliest discoglossid yet recognised. An association of Eodiscoglossus with Albanerpeton and a Marmorepeton-like salamander may have characterized certain freshwater ecosystesm in Europe for about 50 million years from the Bathonian to the Barremian-Aptian. The fossil record of frogs prior to the Cretaceous is poor. The single specimen of Triadobatrachus from the Lower Triassic of Madagascar demonstrates that stem-anurans with just a few anuran skeletal characteristics had evolved by the beinning of Mesozoic (Rage and Rocek 1986, 1989; Milner 1988). However, no other Triassic anurans are known and a few frogs have been described from Jurassic rocks, although these are all crown-group represenatives with the full suite of anuran skeletal characteristics. They are known from eight localities and are reviewed in the discussion. The Middle Jurassic frog material described here was obtained from the microvertebrate assemblage in the Kirtlington Mammal Bed at Kirtlington in Oxfordshire from which Freeman (1979) first recorded frog material. It represents the first discoglossid frog to be reported from pre-Upper Jurassic rocks and also the earliest known critically determinable frog material from Europe. The specimens described and figured here were collected either by Professor K.A. Kermack and colleagues or by Mr. E.F. Freeman and have been donated to the Department of Palaeontology, British Museum of Natural History (BMNH). Mr. Freeman is undertaking paleoecological work with his collections and the specimens collected by him retain his catalogue number (prefixed by EF). Comparative study was also made of Eodiscoglossus material at the Museum National d'Histoire Naturelle, Paris (MNHN).
|
