Actually, ichnofossils(tracks) of the earliest "pre"- dino reptiles from the Permian are found in the Coconino Fm(the Permian strata) .The top formations of the Canyon are actually Triassic marine sediments, so we really wouldnt expect many dinosaurs, however there were some parapsid reptile chunks from the Chinle members and other memebers of the Moenkopi Fm.These, while not officially dinosaurs, were considered warm blooded marine reptiles.
Not everyone has access to GEolEx so that the component stratigraphy of the CAnyon could be referenced.
I dont see that David suffers from any lack of capacity because of his question.
More than Davids question , the Grand Canyon stratigraphy serves as a great book wherein the history of the earth (at least the local portion of the earth from the mid PreCambrian to the Triassic) is presented in a good sequence and serves as a wonderful tool to discuss predictability and falsifiability. The Creationists (sorry to get up on the box again) have hoodwinked the national park service to actually allow the publication and sales of the "Creationist view of the Grand CAnyon" and have it sold in the Rim Gift Shops without major comment.
The USGS had, during the Bush years, complained about this pamphlet when it was being proposed and written. Bushies view on science was that these "alternative views" should be preached and made available as valid science.
The "alternative" view on the Grand CAnyon is full of error and lies, (Just like the Biblical mention of behemoth and leviathan are used as some validation of the mention of dinosaurs and man being contemporary species).
The Bible does not mention anything that can be construed as dinosaurian. The description of behemoth can be an elephant, a hippo, or a komodo dragon.