Hoffmanni was a Mosasaur that deviated from the norm by adopting a new kind of predation. It resembled the early placodont reptiles of the Triassic, like Placodus, by specializing in eating tough-shelled prey such as shellfish, turtles, and ammonites. Its diet was previously speculated based on its teeth and jaw structure until two discoveries in Canada in the early 21st century. These findings revealed the full body shape and diet of Prognathodon. One specimen showed the presence of turtle and ammonite fossils in its stomach, along with a 160cm-long fish, suggesting that while Prognathodon was a specialized predator, it was also opportunistic in its feeding.