Climate Change as Driving Force for Evolution

[Anomalocaris]

But that's not what they originally claimed.

You are employing revisionist history.

There is no revision. The fact that "if not A therefore not B" is valid does not logical require "if A, therefore B" to also be valid.

If HSS and HNS coexisted and yet never interbred, that would be strong evidence they were not of the same species. But if they did appear to interbred in some limited way, that does not prove they were therefore of the same species.