Ukrainian Journal of Veterinary Sciences

Biomorphology, transformation, and differentiation of joints and digits of the limbs in vertebrates

Oleg Melnyk*, Oleksii Melnyk, Maciej Zdun

museum@nubip.edu.ua

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Abstract

The study of morphogenesis, differentiation, and transformation of joints and digits of the vertebrate limbs is a fundamental task of comparative and veterinary anatomy, which can be directly integrated into the practice of clinical surgery and orthopedics. In this context, the anatomical and topographical features of the joints and limb autopodia of both extinct and extant vertebrate species are of particular importance. The purpose of this study was to conduct a biomorphological and comparative anatomical analysis of the patterns of evolutionary transformation, differentiation and muscular architectonics of joints and digits in vertebrates to identify the prerequisites for the occurrence of congenital and acquired orthopedic pathologies of autopodia and limbs. The methods used included dissection, radiography, comparative analysis, photographic documentation, and graphical representation of the study objects. The material for the study was morphological structures of fish (Trigla lucerna, Carassius gibelio forma auratus), museum paleontological resources, and the appendicular skeleton and muscular apparatus of present-day mammals (Equus hemionus, Equus caballus, Sus scrofa var. domestica, Giraffa camelopardalis, Bos taurus, Bison bonasus, Camelus bactrianus, Tapirus terrestris), and Homo sapiens. The biomorphological analysis of Trigla lucerna revealed that the free rays of the pectoral fins function as isolated, digit-like structures with autonomous sensory and motor innervation, while the specific features of their morphology indicated a high degree of specialisation of the locomotor apparatus. Clinical cases of polydactyly, oligodactyly, and polymelia in various taxonomic groups of animals were analysed. It was proved that the identified developmental anomalies call into question simplified evolutionary models of reduction or multiplication of finger elements. Phylogenetic transition of Equidae to monodactyly, due to the dominance of ray III, provided high locomotor adaptation but created a critical biomechanical load on autopodia, which led to the pathogenesis of a number of diseases of the distal extremities, in particular in horses. It was found that the reduction of lateral metapodia limited the compensatory capabilities of the limb, making therapy and prevention of this syndrome impossible without pathogenetically substantiated biomechanical correction and redistribution of static and dynamic forces in the distal region. The obtained data allow differentiating the species norm from developmental pathology, which is important for accurate interpretation of visual diagnostics (computer and magnetic resonance imaging, radiography), development of rational surgical access, and individualisation of orthopedic care for animals in veterinary practice.

Keywords

comparative anatomy; morphological structure; veterinary orthopaedics; autopodial pathologies; locomotion

Suggested citation
Melnyk, O., Melnyk, O., & Zdun, M. (2026). Biomorphology, transformation, and differentiation of joints and digits of the limbs in vertebrates. Ukrainian Journal of Veterinary Sciences, 17(3), 60-91. https://doi.org/10.31548/veterinary3.2026.60
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