БІОМОРФОЛОГІЧНІ ОСОБЛИВОСТІ СКЕЛЕТНИХ ЕЛЕМЕНТІВ ПЛЕЧОВОГО СУГЛОБА ПІНГВІНА ГУМБАЛЬТА

Abstract

The article presents the results and analysis of osteometric research of skeletal structures of the shoulder joint of Humboldt penguin (Spheniscus humboldti). Statistical analysis of the obtained results was made and the percentage ratio of the skeletal structures of the shoulder joint of Humboldt penguin was determined. Certain species features and natural laws were established that point out specific biomorphological adaptations to the «underwater flight». In particular clavicles that accrete into a «fork» are not attached to the sternum. This allowed us to understand certain patterns of their development.The shoulder joint of birds is a complex joint that is formed by bones of shoulder girdle and humerus. A coracoid is the most developed bone of the shoulder girdle. It should be noted that coracoid of birds is characterized by a high degree of development, which is caused by the development of muscles of wing that are fixed to it. The proximal end of coracoid forms a so-called acro-coracoidal process, to which a collarbone is fixed. The distal end of coracoid is connected to sternum, thus forming a coraco-sternal joint that is characterized by low motility.It was found that flipper form of thoracic limb and certain structural features of skeletal structures of the shoulder joint of Sphenisciformes, in particular flattened humerus, caudaly extended scapula, powerful coracoid and furcula are apparently caused by the influence of increased functional loads that have arisen as a result of adaptation to perform rowing functions by wing during rapid and deep swimming under water, because movement under water requires more physical activity.Penguins (Humboldt penguin) are characterized by greatly elongated and expanded in its caudal part scapula (Annex A-3, Fig. 3.5). Its length relatively to the length of the humerus is 150%, and in the widest part - more than 20% of the scapula length. It should be noted that in caudal part of scapula is small, not ossified area that is covered with connective tissue membrane. In studied species acromion of scapula is directed upwards. Furcula in penguin is much expanded in its proximal part. Coracoid is like a column and elongated. Its length relatively to the length of the humerus is 111.1%. Underlying of coracoid is relatively narrow. Width of the coracoid base relatively to the lengths is 29.1%. On the lateral edge of coracoid base is a small appendage, directed proximally. In addition, the lateral edges of coracoid in studied bird species has so-called coracoid window. This window is formed as a result of coracoid ligament ossification. The proximal end of coracoid is bended laterally. Humerus in Humboldt penguin has a flattened shape. Its length relatively to the total length of the wing is 33.5%. Pneumatic fossa is large enough.