Giant rhinoceros-sized tortoise found in Spain is one of the largest in Earth’s history

An ocean giant that once thumped its way across ancient oceans has been recovered in Spain, and it’s one of the largest known species of turtle to ever exist. The shelled behemoth’s pelvis indicates it could have stretched up to nearly 4 meters (13 feet) long when it lived between 83.6 and 72.1 million years ago

The largest sea turtle ever documented was Archelon, an absolute unit that became extinct towards the end of the Late Cretaceous, around 66 million years ago. Now a new specimen gives Archelon a run for his money as the size of his pelvis indicates he was equally gigantic, making him one of the tallest sailors on Earth turtles and the largest that has ever swum in European waters.

The newly discovered species was named Leviathanochelys aenigmatica. The first part refers to the biblical sea beast Leviathan which was actually a sea serpent, but the name alludes to the epic size of L. aenigmatica.

This last part is taken from the Greek name αἴνιγμα (“aínigma”) meaning enigma, which is a nod to the particular anatomical features found on the pelvis and carapace of the species. It was these characteristics that told the study authors that they were considering a new species, and possibly even a new group of turtles.

Leviathanochelys aenigmatica even gave Archelon a hard time.  Image credit: ICRA_Arts

Leviathanochelys aenigmatica even gave Archelon a hard time. Image credit: ICRA_Arts

The prehistoric giant was recovered from the locality of Cal Torrades in northeastern Spain, where it is believed to have been hiding under the surface for around 80 million years. This takes its lifespan back to the Campanian era, a time when rising sea levels saw the ocean reclaim coastal areas while predatory beasts like the Spiral-jawed helicoprion roamed the waters.

Ancient remains include the turtle’s pelvis and parts of its shell. A unique bone structure on its pelvis indicates that the find represents a new taxon of turtles as this curious feature has not been observed on the remains of other species. The authors suggest its function may have something to do with unique respiratory anatomy.

Its gargantuan size is an example of convergent evolution because until now the giants of the turtle world existed in North and South America. Evidently, gigantism emerged in multiple lineages of turtles around the world, resulting in species with colossal shells drifting across the planet.

Size comparisons for the extinct giant tortoises Archelon, Leviathanochelys aenigmatica and a human

Size comparison for three turtles and one human. Image Credit: (c) IFLScience and Ivan_Sabo/Shutterstock

To date, the largest sea turtles to ever navigate the oceans, such as the protostegidae Archelon and Protostega, were thought to have been restricted to North America during the Late Cretaceous (Campanian-Maastrichtian),” wrote the authors.

“The discovery of the new, gigantic and bizarre chelonioid Leviathanochelys aenigmatica marine deposits from the Middle Campanian of the southern Pyrenees, which rival in size Archelonhighlights the diversity of sea turtles and how the phenomenon of gigantism of these groups also occurred in Europe.

The study was published in Scientific reports.

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