In a study published in PLOS Computational Biology, researchers created a computer model of how the huge reptile moved. Plesiosaurs grew to be between 8 and 46 feet long, and all had four flippers. The researchers were surprised to find that the most efficient way of moving such a large body through the water was for the plesiosaur to use just its front two flippers, just like a penguin uses its wings.
"Plesiosaur swimming has remained a mystery for almost 200 years, so it was exciting to see the plesiosaur come alive on the computer screen," Adam Smith, a paleontologist who worked on the paper said in a statement.
See their computer models in the animation below: