Still does not answer my question.
Why is it so hard?
What predictions that are testable can be made that will confirm or deny their “challenge to long held assumptions”?
Eg what should we expect to see in comparative tetrapod genomics and tetrapod fish comparisons that we would not see if the “long held assumptions” were correct?
What had been expected if the “long held assumptions” were correct is more rapid structural diversification among organisms colonizing new environments than would be found among organisms that remained in the original environments. The prediction that is testable is that the colonizers’ evolutionary change will be more pronounced, while this paper indicates the similarities in change between the two groups.