Sedimentary rock is the best place to look for dinosaur fossils.
Many fossils came from dinosaurs that were covered by sediment soon after they died. As sediment continued to settle on top and turn to rock, water moving through the rock slowly replaced the chemicals in the bones with hard minerals, creating fossils. OK, so you need to look for sedimentary rock. But sedimentary rock has been around for millions and millions of years. You need to find the sedimentary rock that formed during the time the dinosaurs lived.