The Archelon’s name originates from its Greek roots “arke” meaning chief and “chelone” meaning turtle. Or Ruler turtle.
Photo taken at Georgia Sea Turtle Center in Jekyll Island, GA
Archelon is an extinct sea turtle which lived approximately 75 million to 65 million years ago during the Late Cretaceous Period. This giant turtle could live to 100 years old, possibly thanks to taking long sleeps on the seabed. One of the most interesting facts about Archelon is not its great size but its shell. This turtle didn’t have the same kind of hard shell or carapace that modern turtles do today. It had bony type plates on its belly area protecting it from possible attacks from the underside and a leather-like covering that stretched over a framework of bones on its back similar to a roll bar cage protecting it from the top. This is especially important for the Archelon as most of it’s prey lived in the middle depths of the sea. It’s critical for this giant to remain neutrally buoyant in order to navigate to shallow waters or dive into deep waters to find food. If it would’ve had a hard shell, then it most likely wouldn’t have been able to stay afloat while swimming in the ocean. Archelon also had flipper-like arms that allowed it to move through the water quickly. This was an important feature because Archelon would have had to compete with, and occasionally swim very quickly away from, animals such as Tylosaurus a giant sea lizard and Cretoxyrhina a shark about half the size of the Megladon and about 50 million years older.
Just like its present day equivalent, the leather back, Archelon spent most of its life in the water, and came on land only to lay eggs. It is believed that Archelon was a carnivore, eating smaller, soft-bodied animals like jellyfish and squid. Its jaws contained large crushing plates and a strongly curved beak, allowing to thrive on its diet of crustaceans and mollusks such as the four-foot long clam Inoceramus, also found with the Archelon remains. Other distinguishing features include a pointed tail, a narrow skull, a relatively narrow, high-vaulted shell, and a pronounced overbite. The live weight of an Archelon ischyros is estimated at more than 4,850 lb.
Archelon is believed to have survived the mass extinction that wiped out the dinosaurs because of their slow metabolisms and aquatic lifestyles. Having a slow metabolism allows them to survive on less food therefore requiring less energy to hunt for it. They were also protected by the vastness of the ocean as they liked to take extremely long naps on the ocean floor, similar to hibernating.
Archelon lived at a time when a shallow sea covered most of central North America. Most of the known remains have been found in South Dakota and Wyoming. The largest Archelon fossil, found in the Pierre Shale of South Dakota in the 1970s, measures more than 13 ft long, and about 16 ft wide from flipper to flipper. The fossil specimen exhibited by the Museum of Natural History in Vienna is estimated to have lived to be a century old, and may have died while hibernating on the ocean floor.