COMPARATIVE MORPHOLOGY AND MORPHOMETRY OF THE SCAPULA IN THE NIGERIAN INDIGENOUS DOG (Canis lupus familiaris) AND PIGEON (Columba livia)

This study compares the morphological and morphometric characteristics of the scapula in a cursorial mammal, the Nigerian indigenous dog (Canis lupus familiaris, locally known as 'Ekuke'), and an avian species adapted for flight, the pigeon (Columba livia). Ten scapulae (five dogs, five pigeons) devoid of pathologies were sourced from the Department of Anatomy Museum, Olabisi Onabanjo University. Morphological features were evaluated across standard anatomical planes. Morphometric parameters (spine length, acromion dimensions, glenoid fossa radius, coracoid process dimensions, and base width) were measured using digital calipers. Data were recorded as mean ± SEM. Morphologically; the dog scapula presented a broad, flat profile with distinct supraspinous and infraspinous fossae, adapting it for robust muscular attachment. In contrast, the pigeon scapula was narrow and blade-like. A notable divergence was observed in the acromion process (bifid in pigeons, single in dogs) and the coracoid process (highly modified in pigeons, reduced to a rudimentary tubercle in dogs). The dog scapula exhibited larger dimensions across all parameters, with a mean spine length of 9.20 ± 0.15 cm compared to the pigeon's 5.60 ± 0.12 cm. The profound dimensional and structural disparities between the scapulae of the Nigerian indigenous dog and the pigeon are consistent with their respective biomechanical demands terrestrial weight-bearing and cursorial locomotion in the dog, versus the highly specialized aerodynamics of avian flight. These findings provide preliminary comparative data on scapula adaptation in cursorial mammals and volant birds and may serve as foundation for larger-scale investigations.