Poorly conceived.
If people from 2149AD went 85 million years into the past on Earth this could introduce a "grand father paradox" or at the very least a "Temporal paradox" preventing time travel in the first place.
Grand father paradox, by altering the conditions for human life to emerge and therefore send humans back into the past or worse yet, preventing human evolution at all e.g. by making a species extinct that was involved in the selection for modern humans.
Let alone the potential for butterfly effects!
The universe does not like paradoxes. They also generally wreck people's heads.
Hence poorly conceived.