Archelon Ischyros, commonly known as Archelon, was a prehistoric giant sea turtle whose fossilized remnants were discovered in Late Cretaceous strata in North America 100 million to 66 million years ago. The name Archelon is derived from two ancient Greek words, “Arkhe” which roughly translates as being the first, and “Chelone,” meaning turtle. Its scientific term, “Ischyros”, signifies “mighty.”

Because it had a leathery carapace rather than the hard shell found in marine turtles, Archelon is frequently imagined to have been remarkably similar to the leatherback turtle. It’s possible that the carapace had a row of tiny ridges.


Archelon had a cranium that was noticeably long and narrow. It resembled the beaks of raptors because it had a distinct, hooked shape and a sheath covering it. The shell of the Archelon is neutrally buoyant in nature. This is the point at which the body of a fish and other aquatic organisms adapts to prevent it from floating to the surface or sinking to the bottom. 

Archelon skull perfectly preserved noted for its bird-like beak
Archelon skull perfectly preserved noted for its bird-like beak

To overcome this obstacle, the animal’s body alters in ways, including the development of denser, thicker bones that counteract the lifting action of the air in its lungs. This prevents the animal from bobbing around on the surface. The Archelon turtle is estimated to weigh around 4,500 – 5,000 lbs. It could be up to 16 ft across between both flippers and 13.1 feet long from head to tail.


Being carnivorous by necessity, Archelon. Since Archelon is frequently compared to the leatherback turtle, it is likely that it had a similar predilection for consuming cephalopods and jellyfish. Its jaws were designed for crushing, indicating that the turtle consumed huge crabs and mollusks as well. Archelon might have been easily sustained by the many thin-shelled, bottom-dwelling Cretaceous shellfish, some of which exceeded 4 ft in diameter. Archelon might have occasionally picked through the surface water as well in search of food.


Archelon probably had the ability to generate the strong swings required for cross-ocean migration and, if necessary, escape from other aquatic predators. It lived in the northern Western Interior Seaway, a location with warm to mild temperatures where plesiosaurs prevailed. The average depth of the muddy, oxygen-depleted habitat that they thrived in was possibly slightly more than 600 ft, and the water’s typical temperature could have been 63 °F.

Wide Archelon skeleton laid flat in a museum
Wide Archelon skeleton laid flat in a museum

Archelon, on the other hand, was not a bottom feeder; instead, it was required to remain active at the middle to top surface regions where its food was most plentiful. As a result, it needed to be neutrally buoyant in order to adjust to various depths wherever its prey resided.


Archelon only ever ventured onto the shore to lay eggs, just like turtles do presently. On the other hand, these eggs would ultimately hatch, and the young might have had to outrun a horde of predators in order to reach the ocean.

Except for a few species, all contemporary turtles have a regular behavioral pattern of nest excavation. Most turtles create chambers in which to lay their eggs. The female begins to excavate the chamber with alternate scooping motions of the back legs after she locates the preferred nesting place. It is theorized that this originated from Archelons.


Because of the presence of natural predators such as mosasaurs like Allosaurus and perhaps even sharks like Cretoxyrhina, it is likely that Archelon was still not completely protected from predators, especially from strikes on the flippers. Considering that, the size of the shell alone may have been sufficient to keep certain carnivores from just being sufficient to engulf the body in their jaws. 

Archelon noted for its massive flippers
Archelon noted for its massive flippers

At the very least, this would have made an adult Archelon more challenging to catch than other sea reptiles with thinner bodies. It is thought that Arechlon would use its hardened underside plates as a sort of defense mechanism. This was derived from bite marks found alongside different fossils suggesting that they were prone to blind predator attacks.

Facts about the Archelon

  1. Archelon was the largest turtle species to have ever been reported.
  2. Archelon went extinct about 68-66 million years ago.
  3. Archelon, like some species of contemporary turtles, can live for decades and even a century.
  4. Archelon had a bird-like beak.
  5. The largest Archelon recorded fossils were 15 ft long and weighed around 3-3.5 tons.


Why did the Archelon go extinct?

At the end of the Late Cretaceous epoch, the Archelon is thought to have gone extinct. This indicates that it was extinct after 66 million years. Scientists think that it went extinct as a result of climate change, as altered environmental circumstances have a direct impact on the availability of food.

Does Archelon still exist?

Archelon has been extinct for a long time. However, they are one of the largest turtle species, and a significant number of turtles nowadays trace their evolution to the Archelon, albeit they are significantly smaller in size.

Was Archelon impervious to predator attacks?

Archelon shells were notably strong, and they had a large diameter, so it would be essentially impractical for a large predator to bite on the shell or even try to swallow them whole as this would, at the most, scratch the surface of the shell. However, its flippers were made of flesh, making them a target for predators to bite, rendering them immobile.

Who discovered the Archelon?

American paleontologist George Reber Wieland initially discovered the Archelon in 1895. He discovered the species’ first-ever fossil in South Dakota’s Pierre Shale geological structures. He noticed a specimen that had been lacking its cranium. But in 1897, a different individual discovered a petrified turtle skull in the same location.

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