While dinosaurs roamed the Earth, marine reptiles in the order Plesiosauria swam in our planet's prehistoric oceans. Find out which creatures belonged in this group, how they grew to incredible sizes, and how they've captivated both scientists and storytellers alike. ➡ Subscribe: http://bit.ly/NatGeoSubscribe About National Geographic: National Geographic is the world's premium destination for science, exploration, and adventure. Through their world-class scientists, photographers, journalists, and filmmakers, Nat Geo gets you closer to the stories that matter and past the edge of what's possible. Get More National Geographic: Official Site: http://bit.ly/NatGeoOfficialSite Facebook: http://bit.ly/FBNatGeo Twitter: http://bit.ly/NatGeoTwitter Instagram: http://bit.ly/NatGeoInsta Plesiosaurs 101 | National Geographic https://youtu.be/mkw593Qa19U National Geographic https://www.youtube.com/natgeo