Cryptosaurus

Cryptosaurus (meaning 'hidden lizard') is a dubious genus of dinosaur from the Late Jurassic of England, known solely from a partial femur. The sole species, Cryptosaurus eumerus, was named by British paleontologist Harry Seeley in 1869 based on a specimen found by geologist Lucas Ewbank. The femur, about 33 centimetres long, came from the Ampthill Clay Formation of the Oxfordian stage. Though initially thought to be related to Iguanodon, later work classified it as an ankylosaurian of uncertain affinities, and it is now considered a nomen dubium due to the limited remains.