Duncker, H. R. The lung air sac system of birds. A contribution to the functional anatomy of the respiratory apparatus. Ergeb. Anat. Entwicklungsgesch. 45, 1–171 (1971).
King, A. S. in International Review of General and Experimental Zoology Vol. 2 (eds Felts, J. L. & Harrison, R. J.) 96 (Academic, 1966).
Maina, J. N. What it takes to fly: the structural and functional respiratory refinements in birds and bats. J. Exp. Biol. 203, 3045–3064 (2000).
Lockner, F. R. & Murrish, D. E. Interclavicular air sac pressures and vocalization in mallard ducks Anas platyrhynchos. Compar. Biochem. Physiol. A 52, 183–187 (1975).
Plummer, E. M. & Goller, F. Singing with reduced air sac volume causes uniform decrease in airflow and sound amplitude in the zebra finch. J. Exp. Biol. 211, 66–78 (2008).
Akester, A. R., Pomeroy, D. E. & Purton, M. D. Subcutaneous air pourches in the Marabou stork (Leptoptilos crumeniferus). J. Zool. 170, 493–499 (1973).
Rusli, M. A brief report on the development of dorsal air sacs in hand reared Von der Decken’s hornbills (Tockus deckeni). Avian Biol. Res. 13, 87–91 (2020).
Daoust, P.-Y., Dobbin, G. V., Ridlington Abbot, R. C. F. & Dawson, S. D. Descriptive anatomy of the subcutaneous air diverticula in the northern gannet Morus bassanus. Seabird 21, 64–76 (2008).
Richardson, F. Functional aspects of the pneumatic system of the California brown pelican. Condor 41, 13–17 (1939).
Groebbels, F. Der Vogel Vol. I (Borntraeger, 1932).
Strasser, H. Ueber die Luftsäcke der Vögel. Gegenbaurs Morphol. Jahrbuch 3, 179–225 (1877).
Biewener, A. A. Muscle function in avian flight: achieving power and control. Philos. Trans. R. Soc. B 366, 1496–1506 (2011).
Hamlet, M. P. & Fisher, H. I. Air sacs of respiratory origin in some procellariiform birds. Condor 69, 586–595 (1967).
Ulrich, F. in Wissenschaftliche Ergebnisse der deutschenTiefsee-Expedition auf dem Dampfer “Valdivia” 1898–1899 Vol. 7, 319–342 (1904).
Brackenbury, J. H. Airflow dynamics in the avian lung as determined by direct and indirect methods. Respir. Physiol. 13, 319–329 (1971).
Bretz, W. L. & Schmidt-Nielsen, K. Bird respiration: flow patterns in the duck lung. J. Exp. Biol. 54, 103–118 (1971).
Bruderer, B., Peter, D., Boldt, A. & Liechti, F. Wing-beat characteristics of birds recorded with tracking radar and cine camera. Ibis 152, 272–291 (2010).
Lovette, I. J. & Fitzpatrick, J. W. (eds) The Cornell Lab of Ornithology Handbook of Bird Biology (Wiley, 2016).
Pennycuick, C. J. Modelling the Flying Bird (Elsevier, 2008).
Huelsenbeck, J. P., Nielsen, R. & Bollback, J. P. Stochastic mapping of morphological characters. Syst. Biol. 52, 131–158 (2003).
Revell, L. J. Two new graphical methods for mapping trait evolution on phylogenies. Methods Ecol. Evol. 4, 754–759 (2013).
Garde, B. et al. Thermal soaring in tropicbirds suggests that diverse seabirds may use this strategy to reduce flight costs. Mar. Ecol. Progr. Ser. 723, 171–183 (2023).
Hedrick, T. L., Pichot, C. & de Margerie, E. Gliding for a free lunch: biomechanics of foraging flight in common swifts (Apus apus). J. Exp. Biol. 221, jeb186270 (2018).
Sapir, N., Wikelski, M., McCue, M. D., Pinshow, B. & Nathan, R. Flight modes in migrating european bee-eaters: heart rate may indicate low metabolic rate during soaring and gliding. PLoS One 5, e13956 (2010).
Pagel, M. Detecting correlated evolution on phylogenies: a general method for the comparative analysis of descrete characters. Proc. R. Soc. B 255, 37–45 (1994).
Felsenstein, J. A comparative method for both discrete and continuous characters using the threshold model. Am. Nat. 179, 145–156 (2012).
Charles, J., Kissane, R., Hoerhurtner, T. & Bates, K. T. From fibre to function: are we accurately representing muscle architecture and performance? Biol. Rev. 97, 1640–1676 (2022).
Tobalske, B. W. Biomechanics of bird flight. J. Exp. Biol. 210, 3135–3146 (2007).
Owen, R. in The Cyclopædia of Anatomy and Physiology Vol. 1 (ed. Todd, R. B.) 265–358 (Sherwood, Gilbert and Piper, 1836).
Azizi, E., Brainerd, E. L. & Roberts, T. J. Variable gearing in pennate muscles. Proc. Natl Acad. Sci. USA 105, 1745–1750 (2008).
Smith, N. P., Barclay, C. J. & Loiselle, D. S. The efficiency of muscle contraction. Prog. Biophys. Mol. Biol. 88, 1–58 (2005).
Casler, C. L. The air-sac systems and buoyancy of the anhinga and double-crested cormorant. Auk 90, 324–340 (1973).
Boggs, D. F. Interactions between locomotion and ventilation in tetrapods. Compar. Biochem. Physiol. A 133, 269–288 (2002).
Boggs, D. F., Jenkins, F. A. Jr & Dial, K. P. The effects of the wingbeat cycle on respiration in black-billed magpies (Pica pica). J. Exp. Biol. 200, 1403–1412 (1997).
Lawson, A. B., Hedrick, B. P., Echols, S. & Schachner, E. R. Anatomy, variation, and asymmetry of the bronchial tree in the African grey parrot (Psittacus erithacus). J. Anat. 282, 701–719 (2021).
Schachner, E. R. et al. Perspectives on lung visualization: three-dimensional anatomical modeling of computed and micro-computed tomographic data in comparative evolutionary morphology and medicine with applications for COVID-19. Anat. Rec. https://doi.org/10.1002/ar.25300 (2023).
Lowi-Merri, T. M., Benson, R. B. J., Claramunt, S. & Evans, D. C. The relationship between sternum variation and mode of locomotion in birds. BMC Biol. 19, 165 (2021).
Lowi-Merri, T. M. et al. Reconstructing locomotor ecology of extinct avialans: a case study of Ichthyornis comparing sternum morphology and skeletal proportions. Proc. R. Soc. B 290, 20222020 (2023).
Prum, R. O. et al. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature 526, 569–573 (2015).
Cooney, C. R. et al. Mega-evolutionary dynamics of the adaptive radiation of birds. Nature 542, 344–347 (2017).
Jetz, W., Thomas, G. H., Joy, J. B., Hartmann, K. & Mooers, A. O. The global diversity of birds in space and time. Nature 491, 444–491 (2012).
Pennell, M. W. et al. geiger v2.0: an expanded suite of methods for fitting macroevolutionary models to phylogenetic trees. Bioinformatics 30, 2216–2218 (2014).
Revell, L. J. phytools: an R package for phylogenetic comparative biology (and other things). Methods Ecol. Evol. 2, 217–223 (2012).
Maddison, W. P. & FitzJohn, R. G. The unsolved challenge to phylogenetic correlation tests for categorical characters. Syst. Biol. 64, 127–136 (2015).
Uyeda, J. C., Zenil-Ferguson, R. & Pennell, M. W. Rethinking phylogenetic comparative methods. Syst. Biol. 67, 1091–1109 (2018).
Revell, L. J. Ancestral character estimation under the threshold model from quantitative genetics. Evolution 68, 743–759 (2014).
Kissane, R. W. P., Egginton, S. & Askew, G. N. Regional variation in the mechanical properties and fibre-type composition of the rat extensor digitorum longus muscle. Exp. Physiol. 103, 111–124 (2018).
Boggs, D. F. & Dial, K. P. Neuromuscular organization and regional EMG activity of the pectoralis in the pigeon. J. Morphol. 218, 43–57 (1993).
Bates, K. T. & Schachner, E. R. Disparity and convergence in bipedal archosaur locomotion. J. R. Soc. Interface 70, 1339–1353 (2012).
Dempsey, M., Maidment, S. C. R., Hedrick, B. P. & Bates, K. T. Convergent evolution of quadrupedalism in ornithischian dinosaurs was achieved through disparate forelimb muscle mechanics. Proc. R. Soc. B 290, 20222435 (2023).
Macaulay, S. et al. Decoupling body shape and mass-distribution in birds and their dinosaurian ancestors. Nat. Commun. 14, 1575 (2023).