A Practical Guide to Sliding and Surface Semilandmarks in Morphometric Analyses.

Area of Science:

• Evolutionary biology
• Comparative anatomy
• Morphometrics

Background:

• Advances in 3D imaging generate large, high-resolution datasets of specimen reconstructions.
• Traditional landmark methods often fail to capture the full morphological complexity present in these datasets.
• Existing semilandmark techniques face challenges with diverse datasets and absent structures.

Purpose of the Study:

• To demonstrate methods for capturing morphology across diverse 3D shapes using comprehensive datasets.
• To address challenges in applying semilandmarks to comparable regions across disparate structures.
• To analyze the benefits of high-density sliding semilandmarks over landmark-only approaches.

Main Methods:

• Utilized comprehensive 3D datasets of crania from birds, squamates, and caecilians.
• Applied sliding and surface semilandmark techniques to capture high-density shape data.
• Developed and detailed solutions for applying semilandmarks to diverse and incomplete structures.

Main Results:

• Demonstrated effective methods for capturing morphology across highly diverse cranial shapes.
• Identified and provided solutions for challenges in applying semilandmarks to disparate structures.
• Showcased the superiority of high-density sliding semilandmarks for capturing shape variation.

Conclusions:

• High-density sliding semilandmark approaches significantly enhance the quantification of shape in 3D reconstructions.
• These methods offer a powerful tool for studying morphological variation and evolution across diverse organisms.
• The techniques discussed promise to advance the study of organismal form using large-scale 3D data.