Three-dimensional (3D) Geometric Morphometrics of the Carnivora Axis: Shape variation, Allometry

Objective:Axis is an important bone due to the structures it is adjacent to and the contribution it makes to the bony structure of the neck. This bone is also responsible for carrying the neck. Since there is not any similar study in the literature, we wanted to investigate the three-dimensional geometrical morphometry of the second vertebrae cervicales, specifically the axis. For this purpose, 17 axis bones from 8 different domestic species belonging to the carnivora family were analysed. Materials and Methods:CT images of the bones were converted into three-dimensional (3D) bone surfaces. A total of 102 landmarks were applied to the images recorded with the generalised procrustes method. Principal Component Analysis (PCA) was performed with SlicerMorph programme. As a result of this analysis, shape variations of the bones were analysed. In addition, Procrustes Distance and Centroid size values of the bones were measured with the same programme. These values were processed into SPSS programme and the effect of age and weight on size was investigated by regression analysis. Results:The shape changes of the bones were analysed from five different faces (cranial, caudal, lateral, dorsal, ventral). As a result of these analyses, shape variations were observed and these variations were explained. As a result of PCA, PC1 explained 21.04%, PC2 explained 13.6% and PC3 explained 12% of the total variation. In addition, age and weight were statistically significant with centroid size as a result of regression analysis. Conclusion: Additionally, age and weight were found to be statistically significant in relation to centroid size in the regression analysis. In conclusion, the dimensional development and morphological changes of the vertebrae are significantly influenced by both age and body weight.