How do birds differ from earlier vertebrates?

Question

lack of scales?

land egg?

ability to maintain constant body temp?

ability to fertilize eggs internally?

possession of dorsal nerve cord?

Answer 1

None of those.

Birds have scales (check out their legs).

"Reptiles" lay eggs on land just fine.

Dinosaurs and mammals existing well before birds were able to maintain constant body temperature.

"Reptiles" existing before birds have internal fertilization.

The dorsal nerve cord came about hundreds of millions of years before birds existed.

Birds have different sized flight feathers, and an odd air system that's one-way for a good part of its journey.  That's about it for uniqueness.  The pterosauria and dinosaurs had most of the other birdlike features (beak, breastbone anchoring flight muscle, hollow bones, down feathers) before there were birds.  *shrug*

Answer 2

birdss lack teeth...datzz d ony reazn i guess!!!! dt makes birds differnt frm earlier vertebrates....