I think assuming that the dinosaurs didn't take off into space in a pre-Noah ship is dinosaurist. Seriously though, we can't really know that we're the "first conscious being" on Earth. We tend to forget that consciousness and intelligence are not the same thing. Yes, we may be very intelligent relevant to chimps, but an increase in intelligence does not translate to an increase in consciousness. We know from studying humans that most operations are unconscious or unconsciously driven. We also know that there have been many extinction events, and most animals before us didn't have thumbs, so they couldn't make or use tools, even if they were conscious of the possibility. They may have used their environment as tools in ways that are undetectable today.