# Shape and Size Variations in the Astragalus of Large and Small Bovids

## TL;DR

This study examines how the shape of the astragalus bone differs between large and small bovids, revealing useful markers for species identification and biomechanical insights.

## Contribution

The study provides new morphological insights into the astragalus of bovids, highlighting its role in taxonomic identification and functional adaptation.

## Key findings

- Large bovids like cattle have a more rounded and robust astragalus compared to smaller bovids like sheep and goats.
- Goats exhibit a more developed outer edge on their astragalus, likely due to their climbing abilities.
- The astragalus shape serves as a reliable marker for differentiating between large and small bovids and related species.

## Abstract

In this study, shape variations in the astragalus, an important bone of the talus joint, in large and small bovids were investigated. By examining the shape and size of this bone in three cattle breeds, three sheep breeds, and one goat breed, we found clear differences between large animals like cattle and smaller animals like sheep and goats. Cattle had a more rounded and robust astragalus, while sheep and goats showed a narrower and more rectangular structure. Among sheep and goat breeds, the goat had a more developed outer edge, likely linked to its ability to climb rough and steep terrains. These differences are valuable for veterinary anatomy as they provide insights into bone structure and function, while also serving as important markers for identifying species and understanding taxonomic relationships among bovids.

The astragalus acts as a crucial intermediary in the tarsal joint, facilitating the transfer of body weight to the lower extremities while also ensuring both stability and mobility through its articulation with adjacent bones, enabling efficient movement. This study investigates the morphological diversity of the astragalus in three modern cattle breeds, one goat breed, and three sheep breeds using three-dimensional geometric morphometric methods. A total of 225 specimens were analyzed in this study. Large bovids, such as the Holstein and Simmental cattle breeds, had a more developed lateral edge of the proximal trochlea and a more rounded astragalus. In small bovids, the Akkaraman and Morkaraman sheep breeds displayed a more prominent medial edge and a rounded astragalus form, while the Hair goat breed exhibited a rectangular structure with a well-developed lateral projection. The results of this study demonstrate that the astragalus serves as a reliable morphological marker for differentiating between large and small bovids, as well as between closely related taxa such as sheep and goats. These shape variations, particularly observed in the proximal trochlea, reflect functional adaptations to size, body mass, and locomotor demands, making the astragalus a critical element for taxonomic identification and biomechanical analysis.