The ancestors of birds emerged from the early mammals a. true b. false

The above statement is false. The ancestors of birds did not emerge from the early mammals. 
It is now believed that birds evolved from small carnivorous dinosaurs of the late Jurassic. This was made possible by recent discovered fossils from China, South America, and other countries, as well as by looking at old museum specimens from new perspectives and with new methods. Dinosaurs are not mammals but warm-blooded reptiles.