What the author calls "smooth" in those examples are in reality distinct quantum steps of speciation.
(Snort!) Lest I taken for Doris Kearns Goodwin, I'll diligently research where I saw the answer to this one.
Here the estimable cracker writes:
"I see you have a nice collection of small pictures, arranged in chronological order, and affixed to a narrow strip of celluloid. An impressive display, but there is no evidence here. You claim these are moving pictures - but which picture shows the motion?"
Why is it so gradualistic/incremental/evolutionary-looking? Did He not know what He wanted early on? Did He not know how?