Bone anatomy of the pelvic girdle, the thigh and the leg of Myrmecophaga tridactyla (Myrmecophagidae: Pilosa)

The giant anteater (Myrmecophaga tridactyla) is the largest anteater species in the world. It is an animal of terrestrial habits, however, it has some ability to climb tall trees and termite mounds. The hard skeletal structures are of crucial importance, since they join and protect the soft organs and help support the body, shape, and get involved in movement. The appendicular skeleton is an important part of the locomotor apparatus, whose anatomical information in wild species is scarce, making it difficult to interpret data on these bones. This paper aims to describe the pelvic girdle, the thigh, and the leg skeleton in the giant anteater. We used two specimens of Myrmecophaga tridactyla Linnaeus (1758), fixed in a 3.7% aqueous formaldehyde solution. At first, the limbs were disjointed and we removed the skin, viscera, and muscles associated to the bones of the pelvic girdle, the thigh, and the leg in the specimens. Then, they were macerated in boiling water, and, subsequently, placed in a hydrogen peroxide solution. Once clean and dry, the bones were identified and described. The pelvic girdle skeleton in the giant anteater consists of the hip bone, formed by the ilium, pubis, and ischium bones; the thigh consists of the femur bone, and the leg consists of the tibia and fibula bones. In the knee joint region there is the patella, a relatively small sesamoid bone, considering the large size of this animal. The giant anteater have osteological features of the pelvic girdle, the thigh, and the leg similar to those in domestic carnivores, however, some morphological differences are made evident, something which may reflect differences in locomotor patterns.