Pannonius

Pannonius is a genus of extinct ray-finned fish that lived during the Late Cretaceous period. Fossils of Pannonius have been found in Hungary, specifically in the Pannonian Basin, which gives the genus its name. The type species, Pannonius hungaricus, was described in 1996.

Pannonius is characterized by a deep, laterally compressed body shape, a long dorsal fin extending almost to the caudal fin, and a relatively small mouth. Its scales are cycloid. The exact phylogenetic relationships of Pannonius are not fully resolved, but it is generally considered to be within the order Clupeiformes, which includes modern-day herrings and sardines. Its presence in freshwater or brackish environments of the Pannonian region suggests adaptations to these specific ecological niches.

The discovery of Pannonius contributes to our understanding of freshwater fish diversity during the Cretaceous, a period when many modern fish orders began to diversify. The fossils indicate a thriving aquatic ecosystem in what is now Hungary. Further research on Pannonius may shed more light on the evolutionary history of teleost fishes and paleobiogeography of the Tethys Sea region.