English: Dinochelys whitei Gaffney, 1979 - fossil turtle (cast of holotype) from the Jurassic of Utah, USA. (DNM 986, Dinosaur National Monument, Utah)

The chelonians are the turtles and tortoises. They are an ancient group of reptiles with a Triassic to Holocene stratigraphic record. Turtles are most easily recognized by their shell - some forms can retract the head & limbs into the shell when threatened, while other species cannot. Their overall body plan has changed very little since the Triassic - a great example of conservative evolution (but see the transitional fossil turtle Odontochelys semitestacea - en.wikipedia.org/wiki/Odontochelys). Chelonians occur in terrestrial, freshwater, brackish-water, and marine settings.

Classification: Animalia, Chordata, Vertebrata, Reptilia, Anapsida, Testudines, Pleurosternidae

Stratigraphy: Carnegie Quarry Sandstone, Brushy Basin Member, Morrison Formation, Kimmeridgian Stage, Upper Jurassic, ~150 to 156 Ma

Locality: Carnegie Quarry, Dinosaur National Monument, northern Uintah County, northeastern Utah, USA

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See info. at: en.wikipedia.org/wiki/Cheloniidae and en.wikipedia.org/wiki/Turtle and

www.nps.gov/dino/learn/nature/dinochelys-whitei.htm