Why do you keep wanting to divide this group in two?
We even have skeletons of small birds of the time that have no breastbone. Otherwise, they are identical to the other birds that have breastbones.
The big birds, also known as dinosaurs, have no breastbones.
Makes them all birds ~ just with different names depending on whether or not they have a breastbone.
Wait a minute! You just said dinosaurs were birds!
Anyways, were are the intermediates? where is the fossil record? There is NO fossil record to prove this, nor can you explain why dinosaurs didn't have gizzards and a had a completely different digestive system. Where are the birds with razor sharp teeth? What dinosaur was an owl? What dinsaur was a penguin? Why is the DNA completely different? Birds were NOT dinosaurs, they were little birds exactly like they are now.