Archelon Sea Turtle

World’s Largest Sea Turtle

  • Order: Chelonia
  • Suborder: Cryptodira
  • Superfamily: Chelonioidea
  • Family: Protostegidae
  • Genus: Archelon
  • Species: ischyros
  • Late Cretaceous – 74 MYBP
  • Pierre Shale
  • South Dakota

The original fossil specimen of this largest of the World’s turtles was collected from the Pierre Shale of South Dakota in the mid 1970’s. Some initial preparation and stabilization of the specimen was done at that time by Peter Larson of the Black Hills Institute for Siber & Siber of Zurich, Switzerland. This partially prepared specimen was eventually purchased by the National Natural History Museum in Vienna, Austria. Museum staff completed the preparation and mounted the Archelon for display as the centerpiece exhibit in that museum where it remains to this day.

Dr. Kraig Derstler of the University of New Orleans, who has studied this specimen extensively, reports that: “Without exaggeration, the Vienna museum specimen of Archelon ischyros is one of the world’s great fossils.”

Facts about this specimen:

  • The original fossil bone skeleton of this Archelon ischyros is owned by and on display at the National Natural History Museum in Vienna, Austria.
  • The original fossil skeleton was collected out of the Pierre Shale about 45 miles south of Rapid City, South Dakota, USA in the 1970’s.
  • The Vienna specimen is the largest Archelon ischyros skeleton ever collected.
  • This specimen is very nearly complete – the most complete of the Archelon skeletons collected to date.
  • This Archelon skeleton measures about 15′ (4.5m) long from beak to end of tail. The skeleton measures about 16.5′ (5.25m) wide across the carapace from the end of one front flipper to the end of the other outstretched front flipper.
  • The live weight of an Archelon ischyros, is estimated at more than 4,500 pounds (2200 kilos).
  • Archelon has a hooked beak and probably had a very powerful bite. Their beak and mouths seem especially well designed for eating large molluscs, like squid, that inhabited the seas of the Late Cretaceous time.
  • This Archelon ischyros, having lived an estimated 100 years, probably died while brumating (hibernating) and thus partially buried in the mud of the sea floor.

The most often heard comment from visitors is a reference to its very large size. Young and old alike, even those who have seen many large dinosaur and mammal mounts, are awed at the size of the Archelon. Since the sea turtles living in our oceans today are fighting for their survival, the Archelon is an especially poignant exhibit and serves as a reminder of Earth’s many endangered species.

Cast replicas of the original fossil skeleton of Archelon ischyros owned by the National Natural History Museum in Vienna, Austria are produced by Black Hills Institute of Geological Research, Inc., under a special agreement with the Vienna Museum.