Human’s never really got off Earth, but they did manage to not destroy themselves for a good couple hundred years before civilisation collapsed. Another dark age would ensue. Ages would pass forgotten in the ruins that followed. Eventually, the world was unrecognisable. Nature and man having grown so close that they were one and the same. A devolved version of homo sapiens hunted through the wilds again, stalking food through the ruins of the great cities while sleeping beneath the recovering skies.

Another rise-and-fall of a homo sapien civilisation and a few thousand years later evolution kicked in.

The funny thing with evolution is that it does not happen in a linear manner. The fish did not slowly grow small legs and little air-breathing lungs while taking longer and longer strolled upon the shore. No, evolution occurs in violent leaps and bounds when genes suddenly all mutate in strange and wonderful ways. Not all work. Some die off while others become genetic dead ends.

But some mutations thrive so well they become another species entirely.

In cosmic terms, nearly overnight, homo sapiens evolved to homo simbians, and thus formed the murky beginnings of another intelligent civilisation.

The simbians would build great cities of light. They became great explorers and researched the fossils left by their early ancestors. They too struggled to piece together their missing links, as much of history was lost to them. How did they evolve from the strange warm-blooded apes that had dominated this planet? They too had no answers, as evolution hides its footprints in the aeons that follow.

But, alas, the simbians, too, would destroy themselves. Their time would stretch out across many thousands of years, but it would eventually also collapse in on itself. Murky ends suit evolution perfectly, as the planet, like a nearly ageless Petri dish, would mix its various life-forms around and something new would eventually appear.

But with each age, a different Earth emerges.

The planet was much warmer now. The Sun was slowly going supernova and there were only a few thousand years for things to exist before being obliterated. And, as the Sun expanded dangerously, the planet heated up for these years and life adapted.

So it was that homo simbians evolved in great, twisted leaps and bound into homo serpentine gene pool. Homo serpentine was far more suited to the hot, sticky planet that Earth was now. And, from the ruins of its two earlier species, homo serpentine built up quickly. Their minds were built to look around corners and peer into the nooks and crannies of the universe while their cold-blood cooled them and the supernova Sun itself gave them energy. They reverse engineered much of the collapsed technology that the homo simbians had left in across their ruined cities of light, and even some of the trace of the now-ancient homo sapiens species.

The cosmos is agnostic about life. It does not care, it merely is. The Sun was growing bigger. The supernova was building, and Earth had little to defend it and those lives that lived on it from complete annihilation in either the supernova event or the sucking black hole that came afterward.

The serpentines knew this. Above all else, the serpentines feared this. They were the sunset of life on Earth and, for all their intelligence and technology; their scaled minds could not come up with a solution to survive this impending apocalypse. Their technology could allow them to leave the Earth, but the Sun’s growing gravity was a challenge they could barely escape. Even if they did manage to escape it, they neither had enough ships nor enough supplies to recolonize the nearest inhabitable planet.

But then one of them had an idea.

Old archaeological records kept homo sapien theories about what the serpentines thought was time travel. Even the simbians had dabbled in this mysterious science. This scientific path was controversial for a number of reasons. Not least of which was the practical matter of energy. The amount of energy needed to actual time travel would be astronomical and either did not exist on Earth or would destroy the planet. But, luckily, as one young serpentine would point out, everything was going to be obliterated anyway when the Sun went supernova. And, therein lay the answer: the supernova explosion would be the power source they needed.

And so, on that sticky hot Earth, the scaled forms of the homo serpentines all bustled around building a time travel devices to save their species from extinction.

There was one major complication: space. The universe has two variables, space and time. If you change one, you are indirectly changing the other. For example, the Earth is spinning, but it is also rotating the Sun while the Sun is rotating around the Milky Way, and the Milky Way is part of an orbiting set of galaxies circulating through the vast eternity. If you go back ten seconds, you will appear in the middle of space, as the Earth was not there ten seconds ago. If you go back ten thousand years, you will appear in another galaxy, as the Sun was not there ten thousand years ago. And so this problem continues, as a time travel device can actually only change time and not space.

Hence, the greatest scaled minds of the serpentines got together. They built the Great Map of Everything, simulated in the greatest super computer of all-time that tracked everything relative to everything else. At some point, at some time in some past version of this universe, the Earth must have been exactly somehow here again.

But when?

Time was running out. The Earth was no longer warm, heating the cold-blooded bodies of the serpentines, it was now hot. Fires raged permanently and babies were being born mutated from the waves of continuous radiation pounding down on them. From one beautiful scaled species, the homo serpentines were suddenly a myriad bunch of scaled monsters fighting against time to survive.

When was the Syncronised Moment? Where and when could they point that time travel device?

Over long periods, time eventually condenses down to mere moments. It had taken many millennia to get here, thousands and thousands of years of evolution for the homo serpentine to perfect themselves, and centuries of technological progress, but the supernova would take mere days.

The homo serpentine swung their solar panels into the full force of it. They gathered themselves across the planet, huddled into small time travel devices, clutching their loved ones, and they took the nearest-best answer for the Syncronised Moment…and then they flipped the switch.

The rounding of the thousandth decimal place in the answer to the Syncronised Moment does not sound like much. But, over millions and millions of years and nearly endless space, this one-thousandth of a fraction adds up to anywhere between a metre to hundreds of them.

The homo serpentines would time travel. That much did–or will–happen. They would make it back millennia to a primitive, cooler Earth, long before even the mammals appeared on it. It was a bestial, dangerous place long before even the homo sapiens had appeared. The problem is that these few metres that were missed by rounding the Synchronized Moment meant that the homo serpentines did not appear on the Earth, but straight into it.

They appeared–and died–contorted in pain and embedded into the sedimentary layers of rock that fitted around the planet.

And that was the end of that.

Little warm-blooded mammals were scampering around this cooler, primitive Earth. Days went by and nothing changed. The homo serpentine were all dead, the homo simbians were not yet even a flicker of a genetic dream. Thousands and thousands of years passed and eventually the little mammals became more and more plentiful and diverse. Millennia spend by and the mammals grew up and, in leaps and bounds, eventually became homo sapiens.

Little knowing what they were looking at, one day a homo sapien would dig up the old, cold bones of a homo serpentine and wonder was happened to this ancient, mysterious creature? The homo sapiens would gaze in wonder at all these now-ancient bones in all their terrifying otherworldly shapes. Theories would form and books would be written in awe of these discoveries. Vast collections of these ancient bones would be found, collected and painstakingly put back together.

And, over time, a single unanswered question would appear, leaving all the homo sapiens wondering to themselves: What really killed all the dinosaurs?