What did birds evolve from?

I don’t believe theres a straight answer to this question, but there have been many noted similarities between birds and dinosaurs so it is likely that modern day birds may have evolved from small tree-dwelling dinosaurs.

It probably depends to a certain extent on what kind of bird. In the long-run, they evolved from single-celled organisms.

I am pretty sure it is an uncontroversial fact within paleontology that birds evolved from dinosaurs. Actually, many paleontologists would correct me….saying that birds are dinosaurs.

Wabarr is entirely correct.