Martinectes bonneri

Martinectes is an extinct genus of polycotylid plesiosaur from the Late Cretaceous of North America and possibly European Russia. The genus contains a single species M. bonneri, known from multiple skeletons and skulls. Martinectes was historically considered to represent a species of the genus Trinacromerum and later Dolichorhynchops before it was moved to its own genus. It was a large polycotylid measuring at least around 5 metres (16 ft) long.