Birds flap their wings when they run up ramps.  It takes less energy than flying.  This is uncontroversial; it is observable, and science can measure the energy cost.  But for at least eight years now, Ken Dial at the University of Montana has been claiming that this behavior explains the origin of flight in birds (01/16/2003, 12/22/2003). When he first came out with this hypothesis in 2003, Elisabeth Pennisi in the journal Sciencesaid, “I imagine people will continue to argue about the origin of bird flight for a long time.”  There’s been very little argument in the media over the years, though (05/01/2006, 9/22/2007, 1/25/2008); in fact, the BBC News just gave another plug for Dial’s hypothesis with no criticism at all.

In her article “Flap-running in birds is key to flight evolution,” reporter Victoria Gill cheerfully quoted Dial’s colleague Brandon Jackson explaining the origin of flight:

Flap running… lets young birds that cannot yet fly – because of small muscles, small wings, weak feathers, etc – get off the ground and away from some predators,” Dr Jackson told BBC Nature.

And if baby birds can perform these behaviours, benefit from them, and transition gradually to flight in their life-time, we think it’s probable that dinosaurs with (similarly small wings) could have performed these behaviours, benefited from them, and transitioned towards flight over evolutionary time.

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