The Largest Turtle Ever Known To Have Lived Was An Absolute Unit

The Late Cretaceous was a time of ocean giants, with the likes of scarily sharp-toothed mosasaurs and ridiculously long-necked elasmosaurs bigging it up in the seas. But while these might be some of the more famous aquatic reptilian behemoths from this period, they aren’t the only ones. Around 74 million years ago, they were joined by the largest turtle ever to have been documented.

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That turtle is Archelon, and we aren’t overexaggerating when we say this thing was an absolute unit. It measured about 4.6 meters (15 feet) from the tip of its beak to the end of its tail, 5 meters (16.5 feet) from the end of one outstretched front flipper to the other, and weighed more than a whopping 2,040 kilograms (4,500 pounds). That’s roughly the same weight as an adult male rhinoceros.

Such chonkery doesn’t seem to have got in the way of its swimming ability, however, as scientists believe they were quite graceful in the water, moving in a similar way to penguins. Archelon also had a beak, but it was far more like that of a bird of prey than a penguin – prominent and hooked. This is thought to have given it a powerful, deadly bite, one that it may have used on mollusks, as well as soft-bodied sea creatures such as jellyfish.

Archelon snacked and swam in the Western Interior Seaway, a now non-existent stretch of sea that once divided North America. But across the ocean in what would one day become Europe, it had a close rival in terms of size: Leviathanochelys aenigmatica.

First discovered in northeastern Spain in the form of its fossilized pelvis and parts of its shell (also known as a carapace), L. aenigmatica also lived during the Late Cretaceous, and dispelled previous suspicions that giant turtles weren’t to be found in Europe. It’s thought to have been almost 4 meters (13 feet) in length, making it the biggest turtle ever to have swum in European waters. The reference in its name to the massive biblical marine monster Leviathan seems pretty appropriate, then.

Still, it’s all well and good knowing about the titan turtles of days gone by, but which is the biggest nowadays? That title goes to the leatherback sea turtle (Dermochelys coriacea); it might not reach the same scale as Archelon, but a length of around 1.5 to 1.8 meters (5 to 6 feet) is still nothing to be sniffed at.