All I can make out is variation there. It is still a shell, albeit a little different looking but still a shell. I call that variation within it's kind. Thank you for the links.
The usual complaint is that the fossil record doesn't record the fine-grained changes (speciation-level). In the instances where it does, the creo escape is "It's still a shell/dinosaur/fish!" Well, that's speciation, not the formation of a new genus or family.
But, as Gould said, there are plenty of examples of transitions between higher taxa. (Mammals to reptiles are one sterling example.) But they tend to be coarse-grained enough to permit a creo escape of "But where are the transitionals BETWEEN those forms?"
Catch-22 debating tricks are not science.