A landmarking protocol for geometric morphometric analysis of squamate endocasts

Area of Science:

• Paleontology
• Comparative Anatomy
• Evolutionary Biology

Background:

• Geometric morphometrics is crucial for studying vertebrate endocast morphology and diversity.
• Landmarks are fundamental for robust and reproducible analyses in morphometrics.
• Squamate endocasts offer insights into the evolution of lizards and snakes.

Purpose of the Study:

• To define a standardized set of 20 landmarks for analyzing morphological variability in squamate endocasts.
• To ensure landmarks are replicable across the diverse Squamata clade, irrespective of neuroanatomical detail.
• To assess the precision, accuracy, and repeatability of the newly defined landmarks.

Main Methods:

• Defined 20 landmarks on squamate endocasts, considering phylogenetic and ecological diversity.
• Sampled ten species representing a cross-section of Squamata.
• Investigated intraobserver and interobserver error to evaluate landmark repeatability.

Main Results:

• The 20 defined landmarks demonstrate high replicability.
• Preliminary findings indicate that these landmarks capture phylogenetic and ecological signals in endocast shape.
• Measurement error estimates confirm the reliability of the established landmarks.

Conclusions:

• The newly defined landmarks provide a robust framework for studying squamate endocast morphology.
• This methodology facilitates further investigations into squamate endocast disparity using geometric morphometrics.
• The landmarks are suitable for comparative analyses across the Squamata clade.