The Order Xenarthra is represented by a group of animals with peculiar morphological and behavioral characteristics, which distinguish them from other groups of mammals. The order comprises a total of 29 species and probably originated in South America, where it occupies a variety of niches. This study aims specifically to establish the morphological variability of the skull and postcranium of the main genera of Xenarthra from the Amazon region, and to correlate the variation presented with ecological parameters of the animal, such as feeding and locomotion habits. The methodology applied consisted of: 1- measurements made by pachymeter between relevant points of the skull and post-cranium of the genera Dasypus, Cabassous, Euphractus and Priodontes (armadillos), Bradypus and Choloepus (sloths), and Mynnecophaga, Tamandua and Cyclopes (anteaters), totaling 196 cranial and 18 post-cranial specimens; 2 - transformation of the cranial variables into natural logarithm; 3 - statistical analysis (uni, bi and multivariate); 4 - determination of the brachial, crural, femur-humeral, tibio-radial and intermembral indices from measurements taken from the humeral, radial, femur, tibial and pelvic regions; 5 - representation of the diagnostic material for each gender by schematic drawing. The multivariate analysis methods (PC A and UPM GA) and linear regression for the skull region separated the individuals regardless of body size, which is considered here as a reflection of the diversity of dietary habits. Similarly, it was possible to characterize locomotor categories based on post-cranial morphology. These results ratify the close relationship between osteological variation and the ecological parameters peculiar to this class. Such information also serves as a basis for the paleoecological reconstitution of extinct toothless individuals.
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