The Oldest Lepidophagous Fish? A New Genus and Species of Glassfishes (Teleostei, Ambassidae, Limnodapalis gen. nov.) from the Lower Oligocene of the Central Paratethys

We describe an extinct new genus and new species of the glassfish family Ambassidae Klunzinger, 1870 (Teleostei), Limnodapalis insolitus gen. et sp. nov., from a Lower Oligocene (Rupelian) freshwater deposit at Raljin (Babušnica Basin, Serbia). A characteristic feature of this species is the unique shape of the lower and upper jaws, which distinguishes it from all known fossil and extant Ambassidae. The tooth-bearing elements (premaxilla and dentary) have anteriorly concavities that are lined with strong, conical, pointed teeth with slightly curved tips. This specialization of the jaws suggests a unique feeding mode, presumably lepidophagy (scale eating). Limnodapalis insolitus gen. et sp. nov. is possibly the oldest known lepidophagous fish. It occurred in a lacustrine habitat during the Lower Oligocene. The skeleton of the single specimen is incomplete, but important diagnostic characters such as the serration of the preopercle (it carries a row of narrow serrations that increase in length ventrally), and the first preorbital (it carries four long and strong spine-like serrations) are well preserved. The internal structure of the fin spines is compartmentalized, which is typically for fossil and extant Ambassidae. The otolith is narrow and elongated, the narrowest of all known fossil and extant ambassid species.