I feel like the scope of this is very broad. As I read it, it appears to be "a creature that is extinct from the perspective of one party encounters another party due to time travel". This could reasonably be extended to virtually any example of time travel far enough into the future or past that things have gone extinct in the interval. At some point, we'll need to chop it up into subtropes or something, for example perhaps "extinct creature brought forward" vs. "observer sent back".
I feel like the scope of this is very broad. As I read it, it appears to be "a creature that is extinct from the perspective of one party encounters another party due to time travel". This could reasonably be extended to virtually any example of time travel far enough into the future or past that things have gone extinct in the interval. At some point, we'll need to chop it up into subtropes or something, for example perhaps "extinct creature brought forward" vs. "observer sent back".