Aerobic performance in tinamous is limited by their small heart. A novel hypothesis in the evolution of avian flight.

ABSTRACT: Some biomechanical studies from fossil specimens suggest that sustained flapping flight of birds could have appeared in their Mesozoic ancestors. We challenge this idea because a suitable musculoskeletal anatomy is not the only requirement for sustained flapping flight. We propose the "heart to fly" hypothesis that states that sustained flapping flight in modern birds required an enlargement of the heart for the aerobic performance of the flight muscles and test it experimentally by studying tinamous, the living birds with the smallest hearts. The small ventricular size of tinamous reduces cardiac output without limiting perfusion pressures, but when challenged to fly, the heart is unable to support aerobic metabolism (quick exhaustion, larger lactates and post-exercise oxygen consumption

SUBMITTER: Altimiras J 

PROVIDER: S-EPMC5698454 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature