The First Freshwater Mosasauroid (Upper Cretaceous, Hungary) and a New Clade of Basal Mosasauroids

Abstract

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.

Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

“…Taxonomical, palaeoecological, palaeobiogeographical, and taphonomical investigations of the Iharkút material arewell documented Makádi et al, 2012; Venczel 2012, Ősi et al, 2012;Botfalvai et al, 2014;Makádi and Nydam, 2014;Prondvai et al, 2014;Csiki et al, 2015;Rabi and Sebők, 2015), however, detailed description and interpretation of the Iharkút sedimentary basin and palaeoenvironment is still missing.…”

The first known chamopsiid lizard (Squamata) from the Upper Cretaceous of Europe (Csehbánya Formation; Hungary, Bakony Mts)

“…1), was discovered in 2000. Since that time, it has yielded remains of lepisosteid and pycnodontiform fishes (Ősi et al, 2012b), albanerpetontid and anuran amphibians Venczel, 2010, 2012;Szentesi et al, 2013), bothremydid turtles (Rabi et al, 2012), the first known freshwater mosasaur Pannoniasaurus (Makádi et al, 2012), alligatoroid, ziphosuchian and heterodont eusuchian crocodiles (Ősi et al, 2007; Ősi et al, 2012b), azhdarchid pterosaurs (Ősi et al, 2005), a rhabdodontid ornithopod (Ősi et al, 2012a), the ceratopsian dinosaur Ajkaceratops (Ősi et al, 2010b), the basal nodosaurid ankylosaur Hungarosaurus (Ősi, 2005;Ősi and Makádi, 2009), theropods (Ősi et al, 2010a), and enantiornithine birds (Dyke and Ősi, 2010) as well as well-preserved remains of lizards (Makádi, 2006(Makádi, , 2007Ősi et al, 2012b).…”

Répteis que um dia dominaram os mares

“…Um grupo adicional de répteis marinhos restriroll 1988, Pough et al 1999, Benton 2006. Apesar de o nome ser associado ao rio Meuse (o local geográfico onde os fósseis foram encontrados), a grande maioria dos mosassauros vivia em ambiente marinho (ver Makádi et al 2012). O crânio da maioria dos mosassauros era alongado, especialmente na parte frontal (Carroll 1988, Pough et al 1999.…”