Hoffmanni was a late Mosasaur that showed a trend towards a different kind of predation that saw it living like the much earlier basal placodont reptiles of the Triassic such as Placodus. This means that Prognathodon specialized in eating tough shelled prey items like shellfish, ammonites, and turtles. The diet of Prognathodon was for a long time just speculation based upon the teeth and jaw construction, but two discoveries in Canada in the early years of the twenty-first century not only revealed the full body shape of Prognathodon but the diet as well. One specimen revealed the presence of turtle and ammonite fossils located where its stomach would have been. Interestingly it also had a one-hundred and sixty centimeters long fish in its gut, suggesting that while Prognathodon was a specialized predator, it was also opportunistic in its feeding.