THE MASTICATORY APPARATUS OF THE ARMADILLO EUTATUS (MAMMALIA, CINGULATA) AND SOME ALLIED GENERA - PALEOBIOLOGY AND EVOLUTION

The eutatines are a group of fossil armadillos traditionally regarded as herbivorous due to the particular morphology of the skull and teeth . Nevertheless, they have never been the subject of a detailed morpho- functional analysis. The masticatory apparatus of Eutatus (late Plioce ne-early Holocene) is analyzed and compared with other eutatines (Proe utatus and Stenotatus from the Miocene, and Doellotatus and Ringueleti a from the Pliocene) and with living armadillos (Euphractus and Dasypu s). The masticatory muscles were reconstructed from origin and inserti on scars; the occlusal pattern and mandibular movements were determine d through the study of the craniomandibular joint, the shape and arran gement of the teeth and the symphysis, and the moment arms of the line s of action of the masseter and temporalis muscles were estimated. Sku ll and mandible shapes were compared using the Procrustean method Resi stant-Fit Theta-Rho-Analysis (RFTRA). The analysis of the masticatory apparatus of the eutatines allows us to state that Eutatus and Proeuta tus exhibit the most specialized morphology known for an herbivore wit h an armadillo-like skull pattern. Additionally, we can identify a mor phological group from the Miocene Stenotatus to the Pleistocene Eutatu s, including the Pliocene Doellotatus and Ringueletia as intermediate stages of a morphological line; Proeutatus deviates from this pattern. This morphological separation may reflect an early dichotomy within t he well-defined clade of eutatines.