I am trying to read the geological history of Oregon, and understand it. Right now I am at the early dinosaurs, but all there is of Oregon at this point are some islands off the coast of Idaho. Those islands became Northeastern Oregon later on.
Hence no dinosaurs in Oregon, other than aquatic ones, which are not officially dinosaurs.
It is impossible to fathom the amounts of time involved in evolution, plate tectonics, etc., from the standpoint of one human lifetime, which is all any or us get.