According to scientists, a giant turtle the size of a great white shark roamed the oceans around 80 million years ago.
It was one of the largest ever – measuring over twelve feet long and weighing about two tons.
The remains unearthed in the southern Pyrenees, northeast Spain, consist of a fragmented but nearly complete pelvis and parts of the upper shell, or carapace.
They date from the Campanian age, between 83.6 and 72.1 million years ago. The new species was named Leviathanochelys aenigmatica.
It is the largest sea turtle ever discovered in Europe – second only to Archelon which lived around the former continent of North America.
Corresponding author Dr Angel Lujan, from the Autonomous University of Barcelona, said: “The large body size could have evolved in response to the unique habitat conditions of the seas of the European Cretaceous archipelago.”
The specimen has a distinctive bone that projects forward from the front of the pelvis.
This feature differs from other sea turtles – indicating that Leviathanochelys represents a new group of ancient sea turtles.
Dr Lujan said: ‘This protrusion may be related to the respiratory system. This supports the hypothesis that Leviathanochelys had an open marine pelagic lifestyle.
Based on the size of the pelvis, the authors calculate that Leviathanochelys could have reached a body length of up to 12 feet 3 inches (3.74 meters).
They estimate that the maximum width of its pelvis was almost three feet (89 cm) – slightly larger than that of Archelon. The length was a bit smaller at 1 foot 4 inches (39.5 cm).
Dr Lujan said: “This makes Leviathanochelys the largest sea turtle ever discovered in Europe, and one of the largest found anywhere in the world.”
Archelon lived about 70 million years ago towards the end of the Cretaceous. It reached 15 feet long (4.6 meters) and weighed up to 3.2 tons.
In contrast, no known European sea turtle, extinct or alive, has exceeded five feet in carapace length – until now.
Dr Lujan said: ‘To date, the largest sea turtles to ever navigate the oceans, such as Archelon, were thought to be restricted to North America during the late Cretaceous.
“The discovery of the bizarre new gigantic Leviathanochelys from the Middle Campanian marine deposits of the southern Pyrenees, which rivals Archelon in size, sheds light on the diversity of sea turtles and how the phenomenon of gigantism in these groups also occurred. in Europe.
“Despite the rarity and fragmentary nature of the individual, the new evidence not only increases the taxonomic diversity of Late Cretaceous sea turtle biota in Europe, but also opens a new avenue of exploration and raises new questions, in order to resolve the evolutionary mechanisms and ecological pressures that could have favored the independent evolution of colossal sea turtles in several lineages, particularly during the Late Cretaceous.
He added: “These findings indicate that gigantism in sea turtles developed independently in different lineages in North America and Europe.”
Male great white sharks average 11 to 13 feet, although females are larger – reaching 15 feet on average.
Leviathanochelys is described in the journal Scientific Reports.