The discovery of an exceptionally well preserved specimen of GJyptodon clavipes Owen permits a morphofunctional analysis of the hyoid apparatus. The specimen was recovered from the cliffs of the Salado River, close to General Belgrano, Buenos Aires Province, Argentina. The morphological modification of the apparatus apparently occurred in response to the migration of the masticatory apparatus below the neurocranium that occurred in the evolution of glyptodonts. It is characterized by the fusion of the stylo, epi and ceratohyoid bones of each side into a vertical rod designated here as the sigmohyoid, which is notable also for its general robustness and the great development of the areas far muscular insertion. While other muscles are reduced, the geniohyoideus and ceratohyoideus acted antagonistically, producing powerful movements of protraction and retraction of the tongue, respectively. The tongue would have been more important in the reworking of food in the oral cavity than in food intake.

Fil: Vizcaíno, Sergio Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina

Fil: Scillato, Gustavo Juan. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina

Fil: Pérez, Leandro Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina