Fig 1.
Humerus morphological variation.
(A) Humerus between-groups principal components analysis (PCA) morphospace showing major axes of shape variation. (B) Warps illustrate representative humerus morphologies at each point in morphospace. (C) Subplots show positions of non-mammalian synapsid subgroups, relative to the convex hulls of the three extant groups. Axes are labeled with the percentage of between-groups variance explained. See S11 Fig for a comparison between PCA and bgPCA results. The data underlying this figure can be found in S1 Table and S1 Data.
Fig 2.
(A) Performance surfaces of seven measured functional traits. (B) Trait weightings of adaptive landscapes calculated for individual species plotted onto the phylogeny. (C) Weightings of adaptive landscapes reconstructed at ancestral nodes plotted against a simplified phylogeny of non-mammalian synapsids. The data underlying this figure can be found in S1 Table and S1 Data.
Fig 3.
Adaptive landscapes and underlying trait weights.
(A) Trait weightings of adaptive landscapes calculated for major extant and fossil groups, which maximize the performance of the group mean humerus shape. (B) The reconstructed adaptive landscapes for each group, showing performance peaks and valleys across morphospace. Fossil taxa are indicated by the gray outline. The data underlying this figure can be found in S1 Table and S1 Data.
Fig 4.
Transitional ‘sprawling-parasagittal’ landscape.
(A) Composite sprawling landscape (reptiles, salamanders, monotremes, and non-synapsid fossils), and (B) parasagittal (therian) landscape, (C) overlaid to create a transitional ‘sprawling-parasagittal’ landscape. (D) Density plots of scores on the transitional ‘sprawling-parasagittal’ landscape plotted for major extant and fossil groups. Points represent individual specimen scores. The data underlying this figure can be found in S1 Table and S1 Data.
Fig 5.
Evolution of sprawling and parasagittal posture.
Scores on the transitional ‘sprawling-parasagittal’ landscape are plotted on the phylogeny of all specimens, illustrated with select humeri. Stars indicate shifts in evolutionary regime for Synapsida identified by SURFACE (see Methods). Nodes labeled with letters; S, Synapsida, T, Therapsida; C, Cynodontia; M, Mammalia; Th, Theria. The data underlying this figure can be found in S1 Table and S1 Data.
Fig 6.
Pareto optimality across synapsid evolution.
(A) Functional adaptive landscapes reconstructed for major ancestral nodes within synapsid evolution and (B) the Pareto landscapes created by combining these landscapes together. Pareto optimality for a group of taxa is defined based on their ancestral peak, and the peak of the next major node. (C) Pareto optimality plotted on the non-mammalian synapsid phylogeny. The data underlying this figure can be found in S1 Table and S1 Data.