Question

Why do birds like emu, ostrich cannot fly?

Answer 1

Explanation:

Ostriches, emus, cassowaries, rheas, and kiwis can't fly. Unlike most birds, their flat breastbones lack the keel that anchors the strong pectoral muscles required for flight. Their puny wings can't possibly lift their heavy bodies off the ground.

Answer 2

Answer:

Emus, ostriches, kiwis, rheas, cassowaries and tinamous all belong to a group of birds called ratites. ... Of these, only tinamous can fly. Scientists studied the regulatory DNA of these birds to learn why most of them can't fly. The researchers found that mutations in regulatory DNA caused ratites to lose flight.