Thalassomedon (from θάλασσα, "sea" and Μέδων, "lord" or "ruler", meaning "ruler of the sea") is one of the largest elasmosaurid dinosaurs. It has a total length of around 11 meters. Its neck is also very long, consisting of 62 vertebrae and measuring around 6 meters in length. The skull is 50 centimeters long, with long teeth measuring 5 centimeters. The flippers have a length of 1.8 meters. Stones have been found in the stomach area of the fossils, leading to the conclusion that these were used for grinding or processing food inside the stomach. This genus of plesiosaurs lived in North America, approximately 95 million years ago. Six specimens have been excavated so far in various states of preservation. Thalassomedon is displayed in various museums in the United States and elsewhere.