Geometric Morphometrics in Phylogenetic Analysis

Geometric morphometrics provides a quantitative framework for capturing, analysing and comparing the shapes of biological structures using landmark coordinates. By removing non‐shape variation through Procrustes superimposition, researchers can plot specimens in a multivariate morphospace and examine patterns of morphological disparity, integration and modularity. When integrated with phylogenetic comparative methods, these shape data enable robust reconstructions of ancestral forms, estimates of evolutionary rates and tests of hypotheses about the tempo and mode of morphological change. The approach is applicable across living and fossil taxa, allowing direct comparisons of disparate lineages and the identification of morphological innovations linked to ecological shifts. Its global significance lies in unravelling deep‐time patterns of divergence, illuminating the processes that generate biodiversity and informing conservation by revealing cryptic phenotypic variation.

Research from Nature Portfolio

Recent studies have applied geometric morphometrics to newly discovered early ornithodiran skeletons, using landmark‐based analyses to quantify cranial and postcranial disparity among dinosaur and pterosaur precursors. These results demonstrated that high morphological diversity predated the radiation of both groups and that key ecomorphological traits emerged well before their classic Mesozoic diversification. In parallel, image‐based three‐dimensional models of theropod and avian skeletons have been used to decouple body shape from mass distribution. Landmark data mapped onto phylogenies reveal that shifts in centre‐of‐mass positions align more closely with functional transitions between terrestrial bipedalism and flight than with simple phylogenetic splits, highlighting modular evolution of limb proportions and mass properties across the dinosaur–bird transition.

Geometric Morphometrics in Phylogenetic Analysis publication trend

The graph below shows the total number of articles in geometric morphometrics in phylogenetic analysis across all publications each year (not limited to Nature Index journals).

Technical terms

Landmark: A specific anatomical point on a structure used to capture shape geometry.

Procrustes superimposition: A method that translates, rotates and scales landmark configurations to a common reference frame, isolating shape differences.

Morphospace: A multivariate coordinate system in which specimens’ shapes are represented, enabling visualisation of disparities and evolutionary trajectories.

Allometry: The study of how shape covaries with size, often examined through regression or principal‐component methods in geometric morphometrics.

Fluctuating asymmetry: Random deviations from perfect bilateral symmetry in paired structures, used as a proxy for developmental stability and stress.

References

1. New reptile shows dinosaurs and pterosaurs evolved among diverse precursors. Nature (2023).
2. Decoupling body shape and mass distribution in birds and their dinosaurian ancestors. Nature Communications (2023).
3. Size, shape, and form: concepts of allometry in geometric morphometrics. Discover Developmental Biology (2016).
4. Analyzing Fluctuating Asymmetry with Geometric Morphometrics: Concepts, Methods, and Applications. Symmetry (2015).