Morphometrics: Introduction to the Analysis of Shape

24 days ago

Morphometrics is the quantitative study of form, including size and shape, used to analyze distinctions, changes, and taphonomic effects.
Principal Components Analysis and Principal Coordinates Analysis are key methods for summarizing multiple variables in morphometrics.
Morphospaces graphically represent quantified shape; theoretical morphospaces use predetermined axes, while empirical ones derive from actual data analysis.
Function of extinct forms is reconstructed via analogies, phylogenetic inferences, biomechanics, trace fossils, and correlations, though some features may be non-functional 'spandrels'.
Landmarks are crucial points for comparing specimens, and traditional morphometrics involves measuring distances between these points.
Phylogenetically independent contrasts correct for phylogenetic biases in statistical analyses, requiring a known phylogeny for meaningful correlations.
PCA and related techniques reduce multiple variables for analysis, applicable beyond morphometrics to fields like ecology.
Data acquisition methods include linear and outline methods like Fourier analysis, with adaptations for 3D morphometrics.
Raup's morphospace exemplifies theoretical morphospaces; advantages include pre-set axes, but some areas may be unoccupied due to functional constraints or taphonomy.
Empirical morphospaces use PCA-derived axes, better occupying the space but requiring reanalysis for new data.

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