Morphofunctional analysis of the hyoid apparatus of Glyptodon cf. clavipesOwen (Cingulata : glyptodontidae).

The discovery of an exceptionally well preserved specimen of Glyptodon cf. clavipes Owen permits a morphofunctional analysis of the hyoid apparatus. T he specimen was recovered from the cliffs of the Salado River, close to Gen eral Belgrano, Buenos Aires Province, Argentina. The morphological modifica tion of the apparatus apparently occurred in response to the migration of t he masticatory apparatus below the neurocranium that occurred in the evolut ion of glyptodonts. It is characterized by the fusion of the stylo-, epi- a nd ceratohyoid bones of each side into a vertical rod designated here as th e sig mohyoid, which is notable also for its general robustness and the gre at development of the areas for muscular insertion. While other muscles are reduced, the geniohyoideus and ceratohyoideus acted antagonistically, prod ucing powerful movements of protraction and retraction of the tongue, respe ctively. The tongue would have been more important in the reworking of food in the oral cavity than in food intake.