Plesiosaur Fin Bone Fossil from Australia

This is a podial (foot bone) from the fin of a Plesiosaur from the Cretaceous of Australia. Plesiosaurs were one of the most successful marine reptile groups, and were once described as “a snake strung through the body of a turtle.” They were divided between the long-necked Elasomosaurs and the short-necked Pliosaurs. They arose in the uppermost Triassic, and appear to have descended from a group of aquatic reptiles called the Nothosaurs. It is thought that the Elasmosaurs were stealth predators, using their long neck to sneak up on prey before lashing out to trap the unwary. They most likely moved through the water using a combination of “flying” and rowing”. Several Plesiosaurs from Australia have been discovered preserved as precious opal, making them of both scientific and aesthetic interest. They had their greatest radiation during the Jurassic, and survived up until the end of the Cretaceous.