Plesiosaurus, tooth, marine reptile Pteranodon The sandstones and shale of

The sandstones and shale of the Front Range were an ideal medium for the preservation of dinosaur and other tracks

a swimming bladder which is open to the pharynx that can function as a lung

Bothriolepis was a bottom feeding armored fish that lived in brackish water and seas

and which may have been used for species or sexual identification

Ornithomimids were long-legged

Plesiosaurus, tooth, marine reptile Pteranodon The sandstones and shale ofPlesiosaurs (meaning "near lizard") were flippered marine reptiles from the Mesozoic Era they were not dinosaurs. Plesiosaurs are divided into two groups: the Plesiosauroids with long, snake like necks, tiny heads, and wide bodies, and the Pliosauroids, which had large heads with very strong jaws and short necks. The first plesiosaur skeletons were found in England by Mary Anning, in the early 1800s, and were amongst the first fossil vertebrates to be