Functional Morphology of the Hyoid Apparatus in Old World Suboscines (Eurylaimides): 1. Anatomical Description

Abstract

The hyoid apparatus of the Old World suboscines (Eurylaimides) was studied by a layer-by-layer preparation of the hypoglossal muscles with subsequent comparative analysis of the morphological features found. The characteristic features of the tongue structure of representatives of all three families (Pittidae, Eurylaimidae, and Philepittidae) were described in detail. It was shown that, in general, the structure of the hyoid apparatus of these birds is similar to songbirds, which are characterized by considerable mobility of the tongue and which have a pronounced ability to manipulate objects with their beak. In addition, details specific to each of the studied groups were identified. The tongue of pittas (Pittidae) has a structure that is the most typical of passerines, while differing in by a significant relative length of some parts of its skeleton. Broadbills (Eurylaimidae), especially carnivorous species, are distinguished by a specifically broad and thick tongue. The tongue of asities (Philepittidae) is characterized by differentiation: its distal part is curled up into a tube, whereas the proximal part forms a platform.