How can gliding snakes and lizards be studied to understand the origins of bird flight? Evolutionary biologist Robert Dudley of the University of California, Berkeley says that newborn birds exhibit the same types of asymmetric movement that these animals create to glide and maneuver in mid-air, which he says supports the hypothesis that birds developed flight by falling from trees.

"Gliding snakes in Southeast Asia, gliding lizards - they’re all highly maneuverable. These are not like paper airplane, launch and glide to target. No, they can take off and land on the same tree that they jumped off of. They can do 180s in midair. They can avoid things. So from day one, all of these gliders actually are highly maneuverable and they carry out those maneuvers by moving their aerodynamic structures asymmetrically, not symmetrically. So it’s another very important argument in support of aerial hypotheses for the origins of bird flight is that basically everything that’s going aerial is maneuverable from day one."