This idea was based on many specimens of tiny teeth and a few jaw fragments. (newscientist.com)
The size and shape of the upper jaw fragment suggests that the creature was about 4 meters long, with some other species in the Helicoprion genus measuring almost twice that length. (sciencemag.org)
They are, in fact, jaw fragments of giant, previously unrecognised ichthyosaurs. (sciencedaily.com)