These fossilized fragments are from the shell of a dry land tortoise, the most common variety of its kind. The shape and structure of the shell indicates this is a land tortoise. Their sizes typically range from 10-12 inches long. These fragments are around 1.25cm thick and measure roughly 2cm x 3cm.
- Catalog Number:
- 51542
- Object/Specimen Description:
- Specimen Count:
- 38
- Locality:
- US Central Plains (NE, KS, IA, MO)
- Collecting Locality:
- North America, United States, Nebraska, Sioux County
- Cabinet:
- 06
- Drawer/Shelf:
- 06
- Upper Level Taxonomy:
- Animalia, Reptilia, Testudines, Cryptodira, Testudinidae
Fossil marine sea turtle, now extinct (Protostega gigas)
Photo by Chip Clark, Smithsonian, National Museum of Natural History
Turtles first appeared on Earth in the Triassic, before the rise of the dinosaurs. The earliest turtle found in the fossil record is an odd-looking animal called Odontochelys semitestacea, discovered in China and dated to about 220 million years old. It appeared to have lived in water and had just a bottom shell (“semi” = half; “stacea” =shelled). Unlike modern turtles, it had a jaw full of teeth. In contrast, another fossil turtle, Proganochelys, dated to a bit later, resembles a modern turtle with a full shell (although it did have a few teeth still, in the middle of its mouth). Paleontologists are not sure whether land turtles evolved from aquatic half-shelled turtles like Odontochelys, or whether Odontochelys evolved from full-shelled ancestors living on land. They are searching for an ancestor to both Odontochelys and Proganochelys to help solve this mystery.