Cambiocenic rostrids are sometimes called turtleparrots, due to their extremely compacted skull and their reduced antorbital fossa, which gives them the appearance of a cross between a parrot and a turtle, a condition that reaches an extreme for brumbles. Their maxilla and dentary are long and robust, filled with small keratinized false teeth organized in dental batteries that allow mastication. A novel muscle, the pseudomasseter, optimizes food mulching and crushing. The resulting bolus will be then digested and assimilated by one of the most efficient digestive systems that any bird has ever evolved.
Ironically, the incredibly specialized skull of brumbles gives them a high diet plasticity.

Mastication

Mastication is the process by which food is crushed and ground by teeth. While the result is the same (the complex food is transformed in a food bolus), intrinsic mechanisms beyond this adaptation are often very different. Ducktails and brumbles are a perfect example: while being both able to ground plant fibers, their masticatory systems work differently.