Extended Data Fig. 9. Scatterplots of melanosome geometry in amniotes and ancestral-state estimation of the diversity of melanosome geometries within Avemetatarsalia.

a–d, Melanosome geometry in amniotes; data from refs. ^2,6. and this study. a, Mammal hair⁶ (n = 1984). b, Squamate skin⁶ (n = 734). c, Pterosaur skin (this study, n = 2115; melanosomes imaged from ten independent samples; purple datapoints) and pterosaur feathers (n = 2173; orange datapoints, this study (n = 1284; melanosomes imaged from four independent samples); black and yellow datapoints, previous studies^2,6). d, extinct and extant bird feathers⁶ (n = 3643). Data from non-avialan dinosaurs are not shown here. Polygon with dark grey shading in (a–d) shows the range of melanosome geometries known for extant and extinct bird feathers. Darker shades in (a) and (d) indicate more than one data point with similar measurements. e, Simplified time-tree phylogeny estimated using the ‘mbl’ branch-length estimation and reconstructed according to the best evolutionary model, i.e.‘equal rates’ (ER) model. The different categories (or ‘states’) of melanosome geometry are: one geometry (in black), two geometries (in red) and three geometries (in green). Only taxa for which melanosome length and aspect ratio was known have been included in our dataset (n = 20). *taxa showing spheroidal melanosomes in addition to any other category. Tupandactylus silhouette (in e) by Evan Boucher from www.phylopic.org.