When humanity came around, metals were found in (relatively) easily accessible places and we could get them out with fairly primitive tools.
As all the easily accessible metals were used up, we got better tools and started digging deeper. And deeper. Today we dig very deep for rocks containing small amounts of metal that we use complicated processes to extract.
If the dinosaurs, or anybody, had been at a comparable level of civilization, the scars of their mining would be very visible. Every mountain that was old enough would be mined out.
There has been a few years since the dinosaurs roamed the Earth, and new mountains has risen. However, most mountains are older than the dinosaurs and none of them bears the scars of mining other than those we humans have made ourselves.
I am assuming that all civilizations want metals. I feel that this is a fairly safe assumption since metals are so very useful. They are hard and strong, they can be forged. Humanity knew nothing better until very recently. Sure, wood is better for some things, bone for some things, glass for some, but the overall champion is the metals.
One of the hallmarks of civilization is that we make trash piles. We don't want our garbage to be in the way of our activities so we pile it up in one place to get it out of the way. This is were all the metal that is "used up" go.
We haven't found any dinosaur trash piles. After so many years, we wouldn't be able to recognize any of the items in the pile, but it would still be an area of the ground with a very peculiar composition, and not looking like any rock we know about. We have fairly good theories on how rocks are formed, and this patch of ground would look wrong in all sorts of ways.
It is possible they were even more advanced than us and recycled everything, but they would still have large concentrations of odd materials in various places. Most notably cities, but also air ports, rail roads and others. Again, we would not understand what we were looking at, but it would definitely look unnatural.