When we talk about survival of the fittest, the first image that often comes to mind is that of giant, vicious predators capable of killing their way to dominance — whether that's Tyrannosaurus rex or the giant ichthyosaurs that once dominated the ocean.
While those titans went extinct eons ago, some of the giant reptiles that lived alongside them — specifically, turtles — focused more on defensive strategies, helping them survive against such fearsome predators. For example, paleontologists discovered a sea turtle fossil in Colombia dating back at least 120 million years ago to the Cretaceous; meanwhile Odontochelys semitestacea, a fossil discovered in China, is a near-turtle relative dating back 220 million years ago.
But which turtles were the largest to ever walk or swim the Earth, large enough to resist the attacks of fierce Cretaceous predators? Here are a few that put our modern-day leatherbacks and Galapagos tortoises to shame.
