time travel be theoretical and so i can give the script some leeway . i also understand the concept that by change just one variable and you can potentially change the way history unfold . what i can not understand and however and be the way the change in time unfolded . we be subject to a series of timewaves which progressively retrograde planetary evolution . while this be a convenient plot device and a it allow our hero enough time to resolve the problem and it make no sense whatsoever . surely and if you change a variable and and that variable have significantly and or even completely and alter planetary evolution and then by the time you come back to the future and the evolutionary process have already be establish and there would be no need for wave . after all and why would a change that happen 65 million year ago need to wait until now to be effective . the fact that the moth be project forward in time may give it some credibility and but the life of that moth 65 million year ago be significantly alter and ergo and any change to evolutionary history would have begin then and and not be dependent upon a return to our current time . to solve the problem and the team go back in time to prevent the change in variable from ever happen . by do this successfully and we see that the change to evolution never happen and and that no one even remember the event . surely and what work for the solution should work for the original change . i like a good rollicking sci fi adventure and but unless it be set in a galaxy far far away it need to have at least some grounding in theoretical possibility to make it truly entertain . good premise and bad plot and reasonable acting and and in all fairness and just a twist on jurassic park . not on my watch again list .