People think birds evolving from dinosaurs makes them not dinosaurs, what do they think a dinosaur is? There isn't a single physical trait unique to birds not found in dinosaurs. Birds evolved from dinosauria long before tyrannosaurus did, which is much closer to our time period.

A triceratops has more unique traits among dinosaurs than birds, it also evolved eons later, is it not a dinosaur anymore merely because it "evolved" from them?

There isn't a way to define the word dinosaur, while excluding birds, that doesn't eject dinosaurs like velociraptors and tyrannosaurus from the word