Lost on the Last Continent book 1
Action! Adventure! Far-future dinosaurs!
Colonel Preston Lost is chasing after a UFO in a plane specifically designed for it (and to skirt the law) when it brings him to an eye -- or rather, he realizes, a vortex. Going through it lands him in the far future, where the sun is enormous and red, the moon is far larger (but recognizable), and dinosaurs have evidently been drawn into the future. Where there are the numerous future races of man (current day humanity being the First), gladiators, a man from a Russian legend, wasps used as a weapons, rings with strange powers, a woman from Atlantis, and much more.