Are there any dinosaurs left?

I'm curious, could you elaborate on the current state of the question 'Are there any dinosaurs left?' Is it a matter of scientific fact that all dinosaurs have indeed vanished, or is there still a remote possibility that some species may have survived through the ages? Are there any ongoing expeditions or research projects dedicated to uncovering any potential remnants of these ancient creatures? And if not, what are the most compelling reasons why scientists believe that dinosaurs are now extinct?