The fossil turtle Notochelone is commonly found in the Richmond area in rocks that are 100 million years old. Notochelone was a small turtle, similar in size to the modern Green Turtle. A much larger turtle, Cratochelone, has also been found in this area but is extremely rare. It may not have lived in the inland sea and the known fossil specimems may have strayed into the inland sea while migrating.
The parts of turtles that are most commonly preserved as fossils come from the shell. The outer layer of the shell is made of scales composed of keratin, like fingernails and hair, which does not fossilise. Usually the large flat ribs from the upper shell (carapace) and flat bony plates of the lower shell (plastron) are preserved. Fossil turtle skulls are resonably rare. This may be because large predators such as Kronosaurus tore their heads off, or because the head may have detached from the body as the soft ligaments began to decay after death.