Morfologia dos ossos do membro torácico do tamanduá-bandeira

Abstract

Morphology of the thoracic limb bones in the giant anteater. The giant anteater has a grayish-brown pelage with white and black tones, its skull is elongated, cylindrical, and there are no teeth. Its tail is long, with thick and long bristles, resembling a flag. This is an endangered species, due to the constant degradation of its habitat, in addition to deaths caused by fires and roadkills. Thus, this paper aimed to describe the morphology of the thoracic limb bones in Myrmecophaga tridactyla, focusing on its main bone accidents. We used two specimens of giant anteater collected on highways in the state of Minas Gerais, Brazil, after death due to being run over. The scapula, humerus, radius, ulna, and the hand bones showed particular characteristics adapted to the species' lifestyle and habits. In general, the scapula resembles that in human beings and the humerus is similar to that in armadillo, the radius and ulna exhibit articular surfaces which enable a wide range of rotational movements in the forearm, the carpal bones are also similar in number and shape to those in human beings, and the fingers are well developed in the giant anteater, having long, strong and sharp claws, especially in the third finger. Thus, the anatomical description of the thoracic limb bones in the giant anteater showed to be important, providing a deeper understanding both of the functional aspects of the thoracic limb and the comparative anatomy of wild animals.

Anatomical and radiographic study of the scapula in juveniles and adults of Tamandua mexicana (Xenarthra: Myrmecophagidae)

“…The supraglenoid tubercle in M. tridactyla is located by the authors in the ventral part of the cranial margin of the scapula (Lima et al, ; Sesoko et al, ), but in Tamandua this part is reported as coracoid process (Taylor, ), which is corroborated with our findings in T. mexicana . Although Taylor () does not describe the supraglenoid tubercle in the scapula figures, the origin of the long head of the m. biceps brachii is graphed just cranial to the glenoid cavity, where we found the supraglenoid tubercle in T. mexicana similar to that proposed by Toledo et al () in extinct xenarthrans such as E. fronto .…”

“…This foramen is not found in Cyclopes because the coracoid has been reduced (McDonald et al, ), but it can be found in other xenarthrans as sloths (Flower, ; Montilla‐Rodríguez et al, ; Toledo et al, ). Due to the ossification of this ligament in Myrmecophaga, the scapular neck becomes less evident, and therefore wider craniocaudally (Lima et al, ; Sesoko et al, ), as occur in Tamandua (Taylor, ; our study). This ligament is not found in domestic mammals (Dyce et al, ; ICVGAN, ).…”

“…Additionally, from this spine towards caudal, a broad surface was developed for the origin of the m. teres mayor (McDonald et al, ; Taylor, ), also m. tensor fasciae antebrachii and the m. subscapular (Taylor, ; our study); however, the complete surface has been named as postscapular fossa (McDonald et al, ; Sesoko et al, ; Taylor, ), but the location and shape of this surface in the scapula of T. mexicana allows us to suggest that the correct name is caudolateral fossa. This surface has also been mistakenly considered part of the infraspinous fossa in M. tridactyla (Lima et al, ) probably because in this study the authors only performed the maceration of the bones, and in their discussion only compared with the human and domestic mammals, and did not compare with previous studies in other anteaters. For human and domestic mammals, there is no specific term for this surface (Federative International Committee on Anatomical Terminology, ; ICVGAN, ), but it can be seen a surface for the origin of the m. teres major in the graphic representations of the scapula in the domestic dog (Evans & de Lahunta, ) and the human (Standring, ).…”

“…The presence of two spines on the lateral surface of the scapula is a characteristic of all xenarthrans (McDonald, Vizcaino, & Bargo, ), which have been named in Tamandua as primary and secondary spines (McDonald et al, ; Taylor, ; Toledo et al, ) or in Myrmecophaga tridactyla as greater and lesser spines (Sesoko et al, ), even in the latter species the lesser spine in another study has been considered as a longitudinal ridge within the infraspinous fossa (Lima et al, ), therefore, to avoid confusion in comparative anatomy with the Nomina Anatomica Veterinaria (ICVGAN, ) and due to its gross anatomical similarity in size (without the acromion) in T. mexicana , we decided to name the second spine as an accessory scapular spine.…”

“…The foramen of the n. suprascapular has had various names in different species of xenarthrans, such as: supracoracoid foramen (Taylor, ), coracoides or scapular foramen (McDonald et al, ), supraglenoid foramen (Sesoko et al, ), coracoscapular foramen (Toledo et al, ) and supraspinous foramen (Lima et al, ). In M. tridactyla , it is considered that this foramen is found in adults due to dorsal ossification to the supraglenoid tubercle (Sesoko et al, ), from a separate ossification centre called procoracoids (McDonald et al, ).…”