Derasmosaurus is an extinct species of rhynchocephalian known from the Pietraroja Plattenkalk of Italy. It was originally considered to be a specimen of Lacerta brevicauda by Costa in 1866, it was later considered a specimen of the lizard Chometokadmon fitzingeri by D'Erasmo in 1915. It was described as a distinct rhynchocephalian genus in 1988.[1] It is distinct from other indeterminate rhychocephalians found in the Plattenkalk.[2] It is considered to be aquatically adapted, and possibly a member of the Pleurosauridae.[3]