Archelon
Largest known turtle, a Late Cretaceous marine giant.
Archelon is an extinct marine turtle from the Late Cretaceous, known only from the Pierre Shale. It is the largest turtle ever documented, with the biggest specimen measuring 4.6 m (15 ft) from head to tail and weighing 2.2–3.2 t (2.4–3.5 short tons).
- field
- Paleontology
- known_for
- Largest turtle ever documented
- time_period
- Late Cretaceous (late Campanian)
- size
- Up to 4.6 m (15 ft) long, 2.2–3.2 t (2.4–3.5 short tons)
- diet
- Hard-shelled crustaceans, mollusks, possibly sponges, jellyfish, squid, nautiloids, or fish
Lore & Background
The genus name derives from Ancient Greek words meaning 'first/early turtle', and the species name means 'mighty' or 'powerful'.
Reader's Guide
Archelon is significant as the largest turtle ever known, providing insight into the evolution and ecology of ancient marine reptiles. It belonged to the extinct family Protostegidae, now considered a completely separate lineage from any living sea turtle, though the leatherback sea turtle was once thought to be its closest living relative. Its leathery carapace, strong foreflippers, and hooked beak suggest it was adapted for open-ocean travel and a diet of hard-shelled prey, jellyfish, or fish. Its extinction may have been linked to the shrinking of the Western Interior Seaway, increased predation on eggs and hatchlings, and a cooling climate. The genus originally included other species (A. marshii and A. copei), but these have been reassigned to Protostega and Kansastega, respectively.
Did You Know?
- Archelon had a leathery carapace instead of a hard shell, similar to the leatherback sea turtle.
- The largest specimen, nicknamed 'Brigitta', measures about 4.6 m (15 ft) from head to tail and 4.0 m (13 ft) from flipper to flipper.
- Its jaws were adept at crushing, and it likely ate hard-shelled crustaceans, mollusks, and possibly sponges.
- The genus name Archelon comes from Ancient Greek words meaning 'first/early turtle'.
Frequently Asked Questions
What is Archelon?
Archelon is an extinct marine turtle that swam the oceans during the Late Cretaceous. It holds the record as the largest turtle ever documented in the fossil record.
How big was Archelon?
The biggest known specimen stretches roughly 4.6 metres (15 ft) from snout to tail and would have weighed between 2.2 and 3.2 tonnes. That puts it in the ballpark of a small automobile, dwarfing every living turtle species.
What did Archelon eat?
Its robust, beak-like jaws point to a diet centred on hard-shelled prey like crustaceans and mollusks. It may also have taken softer-bodied animals such as sponges, jellyfish, squid, nautiloids, or small fish.
When and where did Archelon live?
Archelon inhabited the seas during the late Campanian stage of the Late Cretaceous, roughly 75 to 70 million years ago. Its fossils have been recovered from the Pierre Shale formation in North America.
Why is Archelon important to paleontology?
It pushes the known upper size limit for turtles far beyond anything seen in the modern world. Because it is represented by only a handful of fragmentary bones from the Pierre Shale, it also underscores how much of Mesozoic marine life remains undiscovered.
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