| Named By: | Portis in 1882 |
| Time Period: | Late Cretaceous, 84.9 Ma |
| Location: | France - Rognac Limestone Formation. Spain - Conques Formation, Sierra Perenchiza Formation, Tremp Formation, Vitoria Formation |
| Size: | Unavailable |
| Diet: | Uncertain |
| Fossil(s): | Several individuals |
| Classification: | | Chordata | Reptilia | Testudines | Pleurodira | Bothremydidae | Bothremydina | Foxemydina | |
Polysternon is a genus of turtles in the extinct family Bothremydidae. It was described by Portis in 1882, and contains the species P. provinciale (originally placed in the genus Pleurosternon), which existed during the Cretaceous of what is now France; P. atlanticum, which existed during the Cretaceous of what is now Spain, and a new species, P. isonae, from the Late Maastrichtian of Spain.
The species epithet of P. isonae refers to the municipality Isona i Conca Della in Catalonia, where the type specimen was discovered.