Geometric Morphometric Investigation of Incus in Horse (Equus ferus caballus) and Donkey (Equus Asinus)

In this study, it was aimed to determine the shape of the incus in horse and donkey by geometric morphometric method and to evaluate the shape differences between horse’s and donkey’s incus. The left incus bone of 5 adult horses and 5 donkeys were used in the study. Incus were photographed at same lateral direction. Thirteen homologous landmarks were marked from the photographs using TpsUtil (Version 1.79) and TpsDig2 (Version 2.31) software. As a result of the study, the first principal component explained 38,642% of the total shape variation. In the PC1 plot, samples were clearly clustered by group. Acording to canonical varians analysis, in the wire frame warp graphic, the corpus incudis edges (right, left, and bottom) were flatter in donkeys. Angle at the LM13 level was more pronounced on the crus breve. The apex of the crus longum (Landmark 4, 5, and 6) was wider in donkey. In the study, the morphological features of horse’s and donkey’s incus were determined by geometric morphometric method. This study is important in that it is the first geometric morphometric study on the incus that is one of the ossicula auditus in horse and donkey. We think that the study will contribute to the anatomy of the ossicula auditus in the equide family.