Giant Fossil Softshell Turtle from the Green River Formation - 6 feet long
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We are excited to present this breathtaking fossil softshell turtle (Axestemys byssinus) from the famous Green River Formation in Wyoming, USA. This beautiful turtle spans a jaw-dropping 6 feet long and is the largest specimen of its type discovered in this important locality. It was undoubtedly one of the apex predators of Fossil Lake.
Gigantism in turtles probably came about for the same reasons during the Eocene - when Axestemys swam through Fossil Lake - as it does today. One of the important conditions is a warm, constant tropical or subtropical environment, which is necessary for “cold-blooded” animals to grow extra large. Another factor may be competition between a larger number of similar species in the same geographic area. This occurs in parts of Asia today.
The largest freshwater turtle living in the world today is the highly endangered Yangtze Giant Softshell (Rafetus swinhoei), with only 3 living individual turtles known to currently exist. R. swinhoei can reach a size of 3.9 feet (1.2 meters) and has a distribution limited to parts of the Red River in Vietnam and China.
Softshell turtles belong to a specialized family of turtles called the Trionychidae - a unique group of turtles which lack the hard keratinized shell common to other kinds of turtles. The upper shell (carapace) and lower shell (plastron) of soft shells are covered in soft, leathery skin which is flexible around the edges.
- Location: Kemmerer, Wyoming, USA
- Age: Early Eocene - 52 million years old
- Family: Trionychidae
- Species: Axestemys byssinus
- Specimen Size: 72" / 183 cm long
- Matrix Size: 84" x 60" x 2" / 213 cm x 152 cm x 5 cm
- Ready for wall-hanging - French cleat installed
- Certificate of Authenticity and Letter of Provenance included
This specimen is approximately 95% complete (photos of the specimen prior to the restoration available upon request). The restoration work was mainly done on parts of the shell.
For information on the giant fossil softshell turtles of North America see this article by Natasha S. Vitek.
The Green River Formation is a preeminent fossil locale known as a "lagerstätte" - a deposit that produces specimens with exceptional preservation. It has yielded a wide variety of spectacular vertebrate, insect and plant fossils. Numerous fish species, turtles, lizards, snakes, birds, mammals, insects, palms and flowers thrived in what was once a bountiful subtropical habitat.