I asked if we would likely be able to recognize a transitional at the time. In particular, I was thinking of an evolutionary change that might not show either phsically or in the records. For example, a new way of thinking, or another sense.
So such things certainly could happen through evolution, but might well go unnoticed until far into the future. At that time someone might be sitting around as we are asking much the same questions.
It would seem that it would be nearly impossible to say, looking backwards, when the transition ever occured, but only that it did happen.
Aslan is not a Tame Lion