The Elements of Evolution (23-2-4) Microraptor

 Microraptor
Another feathered bird-like dinosaur appeared 125 MYA: Microraptor. Like Archaeopteryx, Microraptor had a long tail; another glider among the trees. The long tail may have helped stabilize landings.

Microraptor, like some other early birds, had 4 wings. The legs were feathered for lift. Hindwings were for steering. They allowed Microraptor to reduce its turning radius by 40% and tripled the speed of a turn.

Gliding appears in many kinds of animals, from fish to frogs to squid to squirrels. It offers some of the benefits of flight without excessive energy expenditure or specialized structures. Gliding is an easy route to food on the ground. As any child or cat readily demonstrates, climbing up a tree is a lot easier and faster than climbing down.

Only squirrels go up and down trees with equal ease, owing to a special hip joint that allows hind leg rotation to the point where claws are reversed. Microraptor had no such hips.

The 4-wing model was a transitional step to modern bird architecture. Microraptor went extinct well before the Cretaceous closed.