Water frogs are one of the most common fossils in the European Cenozoic, and many taxa have been proposed for Miocene and Pliocene members of the group. Nevertheless, the rare reproductive phenomenon of hybridogenesis, as well as the absence of osteological studies on several living species within the group, makes it almost impossible either to distinguish fossil forms neither to distinguish between the various extant species (Sanchiz, 1998). Here we present the description of eleven articulated fossil water frogs (2 females, 3 males, 1 indeterminate sex and 5 metamorphs) and 353 isolated bones (corresponding to a total of 35 individuals including 4 females and 8 males) recovered from the 2005-2010 field campaigns at the Pliocene (ca. 3.2 Ma; MN15-16) Camp dels Ninots Konservat-Lagerstätte (NE Spain) (Fig. 1). This locality corresponds to a lacustrine sedimentary sequence from maar infill which delivered complete articulated skeletons of large mammals (Alephis tigneresi,Stephanorhinus jeanvireti and Tapirus arvernenis), turtles (Mauremys leprosa) and small vertebrates (as rodents, frogs, newts and several fishes) (Gómez de Soler et al., 2012). Excellent preservation of the fossils was favored by the meromictic conditions of the lake.

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