Question

The two major theories of the origin of flight are the Top-down (arboreal) theory and the Bottom-up (terrestial) theory. However, there is a hybrid theory known as the WAIR theory. Which of these best describes that theory?

a. Wings were used to support gliding from tree to tree and eventually transitioned into a flapping motion
b. Wings were used to help predatory runners to keep their balance or add lift while leaping to catch prey
c. Wings were used to generate lift to takeoff during flapping flight
d. Wings were used in a flapping motion to help climb up steep inclined slopes such as trees
e. Wings were used to generate propulsion while swimming in the water

Answer 1

d. Wings were used in a flapping motion to help climb up steep inclined slopes such as trees

Step-by-step explanation:

According to Top-down ( arboreal ) theory, feathered bird/dinosaur were tree dwelling species. They leaped in between trees to catch prey or avoid predators. They evolved flight mechanism to be able to glide better. According to Bottom-up ( terrestrial ) theory, feathered bird/ dinosaur were ground dwelling species. They used feathers to be able to sprint better and maintain balance while doing so. They also got lift with the help of feathers before running.

Both of these theories either considered origin of flight as a mechanism formed from tree dwelling species or by ground dwelling species. WAIR theory or Wing Assisted Incline Running theory had components from both of them. According to it, birds could run along steep or inclined slopes using wings, so they neither had to be completely tree dwelling or completely ground dwelling. Wings propelled them up the slopes and also conserved their energy.