Fig. 6

Functional phylomorphospace of avian and longipterygid upper jaws, based on mechanical advantage and functional indices, grouped by diet. Grey lines indicate phylogenetic relationships. Data is visualised with PCA (A, B) and LDA (C, D), excluding (A, C) and including (B, D) semi-specialists. In PCA (A, B), PC1 primarily describes AMA, MCH, ACH, and AO and PC2 primarily describes OMA and PMA. In LDA (C, D), LD1 primarily describes AMA, OMA, and ACH and LD2 primarily describes AMA, PMA, and AO. Diagrams of functional indices from Fig. 2 are included roughly in the orientation they are loaded on the plot. See Additional file 1: Fig. S4 for precise character loadings. Diet abbreviations: FrugivoreH hard frugivore, FrugivoreS soft frugivore, GranivoreS swallowing granivore, GranivoreH husking granivore, InvertivoreH hard invertivore, InvertivoreM medium invertivore, InvertivoreS soft invertivore, Tetra Hunt tetrapod hunter. Taxon abbreviations: Lr Longirostravis, LxL large-toothed Longipteryx, LxS small-toothed Longipteryx, Rp Rapaxavis, Sw Shanweiniao