What is the primary evolutionary purpose of the hinged teeth in viperfish?

Answer

To allow the mouth to open wide and engulf large prey without obstruction

The hinged or depressible nature of the teeth is critical for the viperfish. It allows the jaws to open wide enough to capture prey that is often larger than the fish itself. The hinges prevent the long, needle-like teeth from getting stuck or breaking against the predator's own skull or the prey when the mouth closes.

What is the primary evolutionary purpose of the hinged teeth in viperfish?
dietViperfish