The Phenomenon of Hemiextinction illustrates the disappearance of animals from the past and their seemingly extinct nature and their probable possibility of not being extinct at all.

The term, Hemiextinction means half-extinction of species as the name suggests.

Time Travel, however improbable and scientifically impossible it may sound would be developed in the future.

Humanity is currently on the verge of reaching a Kardashev Scale 1. As scientific progress grows exponentially over the coming decades, our score on the Kardashev scale would be catapulted immensely and the rate of the flow of Arrow of Time would only increase.

With the use of Artificial General Intelligence, Volition of Humans and keeping in mind the rate of increase of scientific progress, Time Machine would be invented eventually, when humanity reaches a boastful Kardashev Scale.

Now that we have established the fact, that a time machine would be developed in the future, when the time is ripe, the humans of then would notice the void of other species in their time. At a higher Kardashev Scale, the Archaeologists would study the past of humanity by using a time machine. And by doing so, might as well interfere with the past events in their history.

We know it for a fact that, millions of years ago, dinosaurs existed, and dominated the entire planet. But there was a mass extinction event, that caused their disappearance. There are theories of them, dying due to an asteroid collision, but this is where the time travelers step in. The archaeologists of the future, with Time Machines at their command can go back to the past with ease and rescue all the animals about to become extinct. So is the case with other extinct animals like Dodo, Woolly Mammoth, etc.

Thus, we can conclude that, these seemingly extinct animals may not have been extinct at all, but just transported from the past age to the future by the future humans with the help of Time Machines, and we are unable to perceive it due to the Psychological Arrow of Time.

This gap in Time can be explained by the phenomenon of Hemiextinction, wherein, they existed at a certain point of time, and then the course of Time was altered for their aid, making the humans, who lived in their period of Hemiextinction wonder about their survival and extinction alike. Because once again, due to The Psychological Arrow of Time, we sit in the middle of it all, knowing nothing.