Mirbel somewhere has discussed some such question.
Plants lie under an enormous disadvantage in respect to such discussions in not passing through larval stages.

I do not know whether you can distinguish a plant low from non-development from one low from degradation, which theoretically, at least, are very distinct.

I must agree with Forbes that a mollusc may be higher than one articulate animal and lower than another; if one was asked which was highest as a whole, the Molluscan or Articulate Kingdom, I should look to and compare the highest in each, and not compare their archetypes (supposing them to be known, which they are not.) But there are, in my opinion, more difficult cases than any we have alluded to, viz., that of fish--but my ideas are not clear enough, and I do not suppose you would care to hear what I obscurely think on this subject.

As far as my elastic theory goes, all I care about is that very ancient organisms (when different from existing) should tend to resemble the larval or embryological stages of the existing.
I am glad to hear what you say about parallelism: I am an utter disbeliever of any parallelism more than mere accident.

It is very strange, but I think Forbes is often rather fanciful; his "Polarity" (36/2.