Exceptional Soft-Shelled Turtle

Exceptional Soft-Shelled Turtle
Apalone heteroglypta
Eocene
Green River Formation, Lincoln County, Wyoming
Exceptionally well-preserved turtles such as the present specimen are highly coveted. From the stratigraphic layer known as the F-1 Horizon, or 18-inch layer, of the Green River Formation, this individual lived 51 million years ago in an ancient subtropical environment similar to that of modern day Southern Florida. The ribs extending from the sides of the shell indicate that this is a soft-shelled or leather back turtle. Apalone heteroglypta was described by Edward Cope in 1873 but the genus was originally called Trionyx. This genus lived through the Age of Dinosaurs, survived the K-T extinction and still exists today, though smaller in size than its Eocene ancestor. Modern trionychid turtles are found in Africa, Asia, Malaysia and North America. The superb preservation of fauna from the Green River Formation was aided by the great depth of this prehistoric lake system: the anoxic (oxygen-deficient) condition of the lakebeds discouraged scavengers and slowed decay. Measuring 45 x 38in