Elasmosaurus platyurus is a genus of plesiosaur of the family Elasmosauridae. Styxosaurus lived during the Santonian and Campanian age of the Upper Cretaceous period ( 83.5 - 70.6 mya). It was found in western Kansas, USA. Elasmosaurus was 14 meters (46 ft) long.
Styxosaurus snowii is a genus of plesiosaur of the family Elasmosauridae. Styxosaurus lived during the Santonian and Campanian age of the Upper Cretaceous period ( 83.5 - 70.6 mya). It was found on Hell Creek in Logan County, Kansas, USA. Styxosaurus was 12 meters (36 ft) long.