The long reptilian predator Turturcassis, with its long neck and sinuous build, was a lithe hunter of the flooded forests and deeper rivers, where it preyed upon fish and turtles. Turturcassis had a unique trick for dealing with the turtles that made the bulk of its diet. Retreating into their shells afforded no protection to the armoured turtles. The relentless Turturcassis could plunge its long, tubular head into the head or limb openings of the shell, literally devouring the turtle from the inside out, leaving an empty husk of carapace behind.
Among the turtle species upon which Turturcassis fed was the loggerhead, a species of ocean-roaming sea turtle. Skull Island had its own population of the turtles living in the wider stretches of it primary river. Unlike their pelagic cousins, these turtles lived entirely in the freshwater river. They appeared to be a recent addition to the island's menagerie, not yet distinct enough to warrant a subspecies classification.