Jurassic, ~180 million years agoReputable sourceWell documented
Plesiosaurs Rule the Seas
On the timeline · around Jurassic, ~180 million years ago · The Jurassic
What happened
Long-necked plesiosaurs became dominant ocean predators through the Jurassic and Cretaceous. Fully adapted to open water, they swam using four large wing-like flippers.
Why it matters
Together with the ichthyosaurs, plesiosaurs ruled the Mesozoic seas for tens of millions of years. Centuries later, their fossils would help inspire the legend of the Loch Ness Monster.