Functional Morphology of the Hyoid Apparatus in Old World Suboscines (Eurylaimides): 2. Functional Analysis

Abstract

The structure and functioning of the hyoid and jaw apparatus of birds are closely related to the features of feeding behavior and diet. Analyzing these characteristics together, we can reveal the potential capabilities of this biomechanical node as a whole. Such a complex analysis of the hyoid apparatus of the Old World suboscine passerine birds (Eurylaimides) is presented in this paper. For the birds of each family (Pittidae, Eurylaimidae, and Philepittidae), a functional interpretation of the detected morphological features is proposed (Part 1). Their tongues are highly mobile, this being necessary for performing a variety of specific tasks for each group. The pittas’ tongue is adapted to fast wide-amplitude movements, and it helps in controlling the object at any point of their relatively long and narrow beak. The fleshy tongue of carnivorous broadbills (Eurylaiminae and Smithornithinae) and Pseudocalyptomeninae performs complex manipulations with various objects in its wide bulky beak. The hyoid apparatus of the frugivorous broadbills (Calyptomeninae) helps to mash soft fruits and to push large and hard fruits inside the pharynx. The jaw apparatus of the asities (Philepittidae) is generally adapted to feeding on relatively small berries, which these birds can squash, using a specific wide platform at the base of the tongue. To consume liquid food, asities use the rostral part of the tongue rolled into a tube.