Friday, December 21, 2012

[Paleontology • 2012] Pannoniasaurus inexpectatus • the First Freshwater Mosasaur (Upper Cretaceous, Hungary) and a New Clade of Basal Mosasauroids

Pannoniasaurus inexpectatus
Makádi,Caldwell & Ősi 2012

Mosasauroids are conventionally conceived of as gigantic, obligatorily aquatic marine lizards (1000s of specimens from marine deposited rocks) with a cosmopolitan distribution in the Late Cretaceous (90–65 million years ago [mya]) oceans and seas of the world. Here we report on the fossilized remains of numerous individuals (small juveniles to large adults) of a new taxon, Pannoniasaurus inexpectatus gen. et sp. nov. from the Csehbánya Formation, Hungary (Santonian, Upper Cretaceous, 85.3–83.5 mya) that represent the first known mosasauroid that lived in freshwater environments. Previous to this find, only one specimen of a marine mosasauroid, cf. Plioplatecarpus sp., is known from non-marine rocks in Western Canada. Pannoniasaurus inexpectatus gen. et sp. nov. uniquely possesses a plesiomorphic pelvic anatomy, a non-mosasauroid but pontosaur-like tail osteology, possibly limbs like a terrestrial lizard, and a flattened, crocodile-like skull. Cladistic analysis reconstructs P. inexpectatus in a new clade of mosasauroids: (Pannoniasaurus (Tethysaurus (Yaguarasaurus, Russellosaurus))). P. inexpectatus is part of a mixed terrestrial and freshwater faunal assemblage that includes fishes, amphibians turtles, terrestrial lizards, crocodiles, pterosaurs, dinosaurs and birds.

Etymology. The generic name is derived from the ancient Roman province “Pannonia” in the Transdanubian part of Hungary and “saurus”, New Latin word from Greek ‘sauros’, meaning lizard; the specific epithet “inexpectatus”, meaning unexpected in Latin, refers to the unexpected occurrence of this mosasaur in freshwater environments.

Makádi, L. S.; Caldwell, M. W.; Ősi, A. 2012. Butler, Richard J. ed. The First Freshwater Mosasauroid (Upper Cretaceous, Hungary) and a New Clade of Basal Mosasauroids. PLoS ONE. 7 (12): e51781. doi:10.1371/journal.pone.0051781

Pannoniasaurus inexpectatus | An unexpected lizard from Transdanubia
Pannoniasaurus inexpectatus: World’s first freshwater mosasaur | Scientific American Blog Network