The grandfather paradox is a paradox of time travel in which inconsistencies emerge through changing the past. The name comes from the paradox's common description as a person who travels to the past and kills their own grandfather, preventing the existence of their father or mother and therefore their own existence. Any inconsistency in past events may be regarded as a grandfather paradox.
So how does the Grandfather paradox in the episode End of Extinction effect the Power Ranger universe?
It really is best not to worry about science when it comes to power rangers. A galaxy is clearly a fraction of the real one, and there appears to be air in space. Remember the end of Zeo when they bounced a beam from Earth, to another planet, then another planet, and back to Earth within seconds? Couldn't happen.
In the kingdom of the blind, you're the village idiot.
Also in Super Megaforce when the Armada launched their invasion of Earth the news reports said that the planet had never been through anything like this.I guess the news media just fogot the previous invasion in Countdown to Drestruction.
I suspect Saban figures that the main target audience (younger fans) won't have an encyclopedic knowledge of PR history like hardcore older fans of the franchise.
I think it would have been cool had the past version Keeper just magicly put some Dinosaurs in the animarium so they could survive the comets impact.So in the presant day when the rangers returned to their own time Keeper could have taken Shelby and co to visit them.Thus not messing up the timeline .
I bet that Ninja Steel won't have Dinosaurs as every day animals that didn't go extinct.