While the generally supported theory is that a freak asteroid hit lead to the demise of the dinoasurs, alternative theories suggest that it was no accident.
Consider the likelihood that there is intelligent life on other planets. Most scientists now think that even if life is as rare as hen’s teeth, the number of stars makes it likely that there will be Goldilocks planets circling some of them, and that some of those planets are a lot older than earth. It is also feasible that a new form of propulsion might have been discovered by some of those alien races that enable them to traverse the gulf of space and develop interstellar travel. Be it some form of ion drive, or wormhole jumping, it is not beyond the realms of possibility that these advanced aliens came upon the Solar System many years ago:
They see a young world that has almost arrested development. Dinosaurs have been the dominant species on the planet for million of years. Evolution is so painfully slow, that it is unlikely they will ever devlop into intelligent life even given many more millions of years. Intervention?
Some might argue that an advanced alien race would have a “no interference” policy when coming across inhabited worlds, much as wildlife documentary makers don’t interfere when a lion brings down a gazelle, or a pack of hyenas ambushes a baby giraffe. But what if they have some higher, more lofty goal? What if they believe that they should encourage the development of intelligent life on planets in the multiverse? It might be some quasi-religious drive that spurs this apparent altruism towards giving worlds a helping hand towards more advanced development. Rather like in the film 2001:A space Odyssey, they trigger a rush in progress of apes to man- except that this race visited earth long before the mammals, at the time of the dinosaurs. And perhaps they realised that mammals would never become dominant, and that dinosaurs could never develop into intelligent life. What to do?
Rightly or wrongly they decided to end the dinosaurs. Deflect a metoer to cause extermination of almost all life, but allowing mammals a chance to flourish. Did that really happen? Did aliens play God? No evidence, but it’s a plausible story. One wonders what we earthlings would do if we developed interstellar travel. Would we just leave a planet and its inhabitants to evolve (or not) or would we try to encourage creation in our own image? Well, we can put that question on hold until after we’ve developed a practical means to travel to the stars. Unles there’s life on Mars….