This birds evolved from dinosaurs debate is taken too seriously. It is just dividing the scientific community into two camps that feel they need to fight against each other about it.
Obviously birds evolved from earlier species. Whether it was the dinosaurs line or the reptiles line or amphibians is not important enough to fight about endlessly.
It would be better to just find the specific species that eventually led to birds.
Lots of issues 'divide' the scientific community, not just in biology. How about Global Warming? I do see your point that some divisions are over seemingly trivial points.
Well, a lot of science involves "nailing down the details". Part of the reason is that the whole reason for science is to "fill in the blanks" in current knowledge, whether large or small. The other part is that often the most interesting discoveries turn up only when you're looking way down in what seem to be the trivial details. For example, in the last part of the nineteenth century classical physics explained just about everything (seemingly completely) except for a few minor details like the profile of the black-body radiation curve. When physicists tried to nail down that seemingly minor issue, they discovered quantum physics.
Thanks for your frankness. Summary: "We don't know what happened, but we know it was evolution."