Does Dinasours Ever Existed??

We can't get any more solid evidence of their existence than the presence of their fossils. It would be cool though if we could find live ones living in the earth's deepest waters and remote places.

Aside from bones there have been found eggs, coprolithes, skin or feather impressions (yes some dinosaurs had feathers) and tracks of dinosaurs. The proof gathered is huge and there is no doubt for someone that has a clear mind that dinosaurs existed. You ask what is the need for their existence? I really don't understand the point of your question... What need is there for the existence of men??? Or maybe you mean to ask what can be used from their former existence? Economically - not much... nothing I fear. Scientifically - dinosaurs show many interesting unique features that help us clear many problems connected to so many aspects of natural sciences that it would take me pages just to mention...