Extended Data Fig. 1: Diagram of linear measurements of avian morphology.
From: Macroevolutionary convergence connects morphological form to ecological function in birds
a, Resident frugivorous tropical passerine (fiery-capped manakin, Machaeropterus pyrocephalus) showing four beak measurements: (1) beak length measured from tip to skull along the culmen; (2) beak length measured from the tip to the anterior edge of the nares; (3) beak depth; (4) beak width. b, Insectivorous migratory temperate-zone passerine (redwing, Turdus iliacus) showing five body measurements: (5) tarsus length; (6) wing length from carpal joint to wingtip; (7) secondary length from carpal joint to tip of the outermost secondary; (8) Kipp’s distance, calculated as wing length minus first-secondary length; (9) tail length. Analyses exclude Kipp’s distance, and thus include 8 traits shown here (plus body mass, making 9 traits in total). Illustration by Richard Johnson.
