Odontochelys semitestacea (meaning "toothed turtle with a half-shell") is a Late Triassic relative of turtles. Prior to the discovery of Pappochelys it was considered the oldest undisputed stem turtle. It is the only known species in the genus Odontochelys and the family Odontochelyidae. O. semitestacea was first described from three 220-million-year-old specimens excavated in Triassic deposits in Guizhou, China.