Why did the plesiosaurs go extinct and what factors contributed to their disappearance from the Earth?

PlesiOSaurs went extinct around 66 million years ago, likely due to a combination of factors. The main reason for their extinction is believed to be the mass extinction event that wiped out the dinosaurs, known as the Cretaceous-Paleogene extinction event. This event was likely caused by a massive asteroid impact, volcanic activity, and climate change. These factors led to drastic changes in the environment, including a decrease in food sources and habitat loss, which ultimately contributed to the extinction of the plesiOSaurs.