Table 1.

Summary of results for time-series model fitting for archosauromorph and therapsid clades. Higher Akaike weight (A.W.) indicates a better model fit. µ, step mean; σ², step variance; θ, trait mean for stasis; trait optimum for Ornstein–Uhlenbeck (OU), ω, trait variance; α, constraint parameter. Generalized random walk indicates an evolutionary trend, unbiased random walk indicates significant variation but no trend and OU indicates evolution towards an optimum. No shading and bold text, best model; light shading, non-negligible models (A.W. ≥1/8 best model), dark shading, negligible models (A.W. <1/8 best model).

clade	n	generalized random walk (GRW)		unbiased random walk (URW)		stasis		Ornstein–Uhlenbeck (OU)
		A.W.	μ, σ² (log mm)	A.W.	σ² (log mm)	A.W.	θ, ω (log mm)	A.W.	θ, α, σ² (log mm)
Archosauromorpha	194	0.210	0.005, 0.004	0.700	0.004	0.002	2.397, 0.064	0.088	2.508, 0.040, 0.005
Dinosauromorpha	107	0.585	0.012, 0	0.023	0.003	0.000	2.553, 0.077	0.392	3.198, 0.018, 0
Ornithischia	15	0.239	0.043, 0	0.410	0.004	0.349	2.174, 0	0.002	38.249, 0.001, 0
Theropoda	30	0.463	0.006, 0	0.436	0.001	0.095	2.540, 0.008	0.007	2.371, 0, 0.001
Sauropodomorpha	50	0.271	0.013, 0.002	0.222	0.003	0	2.844, 0.059	0.507	3.031, 0.059, 0.001
Pterosauria	17	0.026	−0.003, 0.002	0.791	0.002	0.184	1.690, 0.015	0	1.723, 0.105, 0
Pseudosuchia	35	0.099	−0.006, 0.003	0.853	0.003	0.044	2.218, 0.036	0.004	2.146, 0.051, 0.004
Aetosauria	7	0	−0.001, 0	0	0	0	2.286, 0	1.000	2.266, 1.317, 0
Therapsida	248	0.288	−0.003, 0.001	0.641	0.002	0.003	1.926, 0.023	0.069	1.590, 0.021, 0.002
Anomodontia	107	0.097	0.009, 0.001	0.418	0.002	0.013	2.322, 0.031	0.472	2.484, 0.097, 0
Cynodontia	68	0.143	−0.001, 0.002	0.630	0.002	0.037	1.781, 0.020	0.189	1.590, 0.021, 0.002
Therocephalia	33	0.032	−0.017, 0.000	0.676	0.001	0.292	1.913, 0.004	0	1.707, 0.091, 0