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Ancient Turtle

an ancient sea turtle swims with a mosasaur and ancient cephalopods
Smithsonian Institution

The first fully marine turtles emerged during the Cretaceous Period, a span of time lasting between 145 and 66 million years ago. By 120 million years ago, they resembled the sea turtles we are familiar with today. The largest, Archelon, measured up to 15 feet from head to tail.

Tags: Sea turtles