Paleontologists have long been mystified by how plesiosaurs were able to propel their massive bodies through the ocean 200 million years ago. The prehistoric marine reptile—which many know as the most commonly attributed "identity" of the Loch Ness Monster—had a body structure that’s practically incomparable to any creature alive today. Rather than the typical tail that can be found on most large sea animals, they used four flippers to maneuver their awkward, long-necked bodies which stretched nearly 50 feet long in some species. As reported in the latest edition of PLOS Computational Biology [PDF], a group of scientists now believe they’ve finally cracked the secret to the plesiosaur’s mobility.

PLOS Computational Biology

Using computer simulations, the researchers were able to test a number of swimming techniques to see how each would work for a particular species of plesiosaur. The most successful animation shows the model flapping its two front flippers in a motion of underwater flight similar to how penguins and sea turtles swim today. The front limbs appear to have provided the creatures most of their power, while the two back flippers were likely used for stability and direction. This makes the plesiosaur fairly unique in the sea creature kingdom, as most aquatic animals like whales and fish generate thrust from their tails. You can watch the full computer simulation in the video below.

[h/t: Gizmodo]