The lid gilltail replaced it's ancestor in Bone River. They are almost exactly like their ancestor, the hook-beak river gilltail, except for one obvious thing. The bottom part of their beaks has migrated downward and now acts like a cover for their "throats". They have adapted this to help defend themselves for the belumbia. When a belumbia tries to drink the blood of the lid gilltail, they close the lid to prevent them from succeeding.
They still impale their prey, but now they have to rip off chunks small enough to fit in their mouths. To achieve this, their top beak can now pivot upwards, so when they kill prey or find a plant, they use it in a manner similar to a knife, slicing chunks off.