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Updated: Oct 25, 2025
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Visualization of Cortical Modules in Flattened Mammalian Cortices
Published on: January 22, 2018
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No modularity at ventral level in the horse skull.
1Department of Animal Science, ETSEA, University of Lleida, Lleida, Spain.
Anatomia, Histologia, Embryologia
|August 11, 2021
Summary
This study reveals clear cranial modularity in horse skulls, specifically within the splanchnocranium and basicranium. This modularity may explain the lack of extreme skull proportions in domestic horses and impact survival under selection.
Area of Science:
- Evolutionary biology
- Comparative anatomy
- Quantitative genetics
Background:
- Morphological integration and modularity describe covariation within biological structures.
- Horse skulls have been studied functionally, but quantitative modularity analysis is limited.
- Splanchnocranium and basicranium are key cranial regions influenced by soft-tissue-hard-tissue interactions.
Purpose of the Study:
- To quantitatively evaluate cranial modularity in the horse skull at a basal level.
- To test the modularity hypothesis for splanchnocranium and basicranium modules.
- To compare integration strength and covariation patterns between these cranial modules.
Main Methods:
- Geometric morphometrics were used to analyze skull shape and landmark data.
- 57 two-dimensional cranial landmarks were applied to 23 Pyrenean Horse Breed dry skulls.
- Partial least squares analyses and Escoufier (RV) coefficient were employed to compare modules.
Main Results:
- A clear modularity was observed between the splanchnocranium and basicranium.
- Integration strength and covariation patterns were assessed using Escoufier (RV) coefficient and partial least squares.
- The findings suggest limited independent evolution of single modules in domestic horse breeds.
Conclusions:
- Horse cranial modularity is evident, particularly in the splanchnocranium and basicranium.
- Integration may enhance survival by aligning selection pressures with variation trajectories.
- The observed modularity could explain the conserved skull proportions in domestic horse breeds.
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