It's always headache inducing trying to sort this out, and my knowledge of CC is nowhere near as good as my knowledge of CT, but here goes...

In 65,000,000 BC, during the war between the apes and the reptites, Lavos falls to the earth. Lavos somehow infects the apes and they start to evolve into what we know now as humans, but with the gift of magic as well. The apes/humans defeat the reptites and become the reigning species upon the planet.

In 12,000 BC, Queen Zeal and the three Guru's, along with Schala Zeal, use the Mammon Machine to create a link to Lavos. It all goes scatty with the Guru's being scattered throughout time, along with Schala's little brother, Janus.

In 600 AD, a man called Magus attempts to summon the legendary immortal Lavos but he is killed in the process by a lone warrior called Frog.

In 1000 AD, a young woman going by the name of Marle is sucked into a time-gate and sent back in time to 600 AD.

(NOTE: This is of course when CT begins, but we'll ignore that for now...)

In 1999 AD, Lavos rises through the planets crust and reigns down fire upon its denizens, killing almost all of them.

In 2300 AD, the human species finally dies out.

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This is the original time-line right? Now, this is where it gets confusing... we all know that when Marle was sucked back in time, Crono and Lucca followed her and eventually they end up in 2300 AD when they discover the advent of Lavos.

The important thing to think about here is how time itself works... if I travelled back two years ago and hacked EoFF, permanently removing it from the internet, the rest of time INSTANTLY changes. I'd not know what I've done since I would have no concept of what EoFF is. Since there is no EoFF, I wouldn't have travelled back in time two years, so I'd STILL be in the present, BUT if I didn't travel back in time, I wouldn't have hacked EoFF, and thus I would know what it is and BOOM! My head explodes.

That's what should have happened. Let me explain...

When Crono and co. see the video in 2300 AD, they go and change time. So, now Lavos is dead right? This means that when they travel forwards to 2300 AD, there is no video of Lavos rising, thus they do NOT defeat Lavos, thus Lavos does rise, thus they do see the video, thus they defeat Lavos, thus they do not see the video, thus they do not defeat Lavos, thus Lavos does rise, thus they do see the video, thus they defeat Lavos... ad infinitum. It's simple; you CANNOT change time.

The events of CC are immaterial. It doesn't matter that the Time Devourer is created and defeated, that just happens. So, what about Schala resetting time I hear you say? Well, let's see how that works...

So, CT happens and Lavos is defeated, thus CC happens. Schala resets it so Lavos is not defeated, thus Crono and co. see the video in 2300 AD, thus they defeat Lavos, thus CC happens again, thus time is reset again, thus Crono and co. see the video in 2300 AD, thus they defeat Lavos... ad infinitum.

Doesn't work still, does it?

I'll leave it there since my brain is melting out through my ear...