However, there is no evidence of a split.
Instead, there is a problem with Sorin. He time traveled alone, then CMG followed. That means there was a time line in which only Sorin emerged in prehistory, and somehow this attempt failed since it took now another time line, in which this time CMG time traveled too.
He couldn't have succeeded as then CMG would have suffered the same fate the other three did, not knowing of the reptite time line and instead appearing in the restored one.
There, a new plot hole to work with. Except, that isn't exactly the plot hole. It's how Sorin entering a TB portal and destroying that Dragon Tooth was able to affect the time line, as that one and the one to appear in 3M BC are not the same anymore thanks to him changing the time line with his time travel.