nested heirarchies as evidence against darwinian evolution

Similar traits certainly do develop by convergent evolution, but they are never nearly as profound as the collection of specifics I've given in the sentence you quote above. The first chordate was a specific animal, a unique species, and no single species has ever evolved twice, or ever conceivably could.I don't dispute that you want this to happen, because it could only happen in a designed world.Convergent evolution could produce worm like species with the superficial appearance of the original chordate, and I'm sure it has many times, just as the killer whale has the external appearance of the shark.And what do you mean by "something else, period"? Mammals are "something else, period". The word "phylum" is just a word used to describe a very broad group of diverse animals that have some identifiable features that relate to their distant common ancestry, so the original prototype species, the "father/mother" of all in the phylum, has to be an ancient animal by definition. So it's like looking at all the mammal descendants in about 400 million more years, when they'll be far more diverse than they already are, and calling them the phylum mammalia 500 million years after the first species that fathered them all.Incidentally, as you seem to think that you're on a planet in a universe that replicates history to the level of exactitude that you've demanded above, do you think that the American war of Independence or the Norman invasion of England will happen again?Or do you agree that a changed world automatically means that they cannot be replicated?

randman, The process is there, is continuing, as evidence by seasquirts to elephants within the chordate phylum. But an organism belonging to a phylum will always belong to that phylum, all its ancestors will always belong to that phylum. They cannot begat another phylum as the rules of classification do not allow it.In other words, no-new-phyla is an artifact of our classification system, evolution continues unabated, however.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

It's responses like this: That Randman feels justify his excursions outside the Forum Guidelines.In his last extended period here, one criticism Randman often made was that board moderation is far easier on evolutionists than creationists. Board moderation's view was that Randman was failing to acknowledge or accept any role his own behavior might have played in the chaos with which his participation frequently seemed associated, but we won't be having that debate again. The recent changes mean I feel no need to convince Randman that he is at fault before taking action, but on the other hand simple fairness demands that I attempt to create an environment as favorable to his success as possible.

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--	Percy
	EvC Forum Director

I believe that Randman is trying to say the following:He claims (and may or may not be right) that say there is a group A of animals composing of hundreds of thousands of different species. It is claimed by evos that one population diverged and became different enough to be part of a new group B. However all the remaining species in A remained almost exactly the same with very little change for hundreds of MILLIONS of years. Why is this the case? Why can't another population of this very large group A diverge? I think what he is suggesting is that no population EVER diverged from Group A to form group B, and that the fossil record simply shows that Group B appeared suddenly in the fossil record.
Now this can easily be disproved if one can show examples of different groups diverging from the parent group which has lived on till now. The lingering doubt exists because the fossil record does not indicate this i.e species suddenly appear.
Personally, I think that random mutation alone may not be able to account for all new traits introduced into a population - there seems to be an unknown process involved here.

What happened was that A branched into B and C. A ceased to exist. Thus A will never diverge again, since extinct populations don't reproduce by definition.

Do you advocate hyper-gradualism then? I thought most evos had moved past that by now.

That's exactly correct.

Mark,Your post does not address my point. We are not discussing the posited evolutionary lines, per se...at least on this point, that theorically occured from the phyla that appeared in the Cambrian explosion or existed then, but why the same process that produced those phyla did not continue to do so for the next 500 million years.

What I said has nothing to do with "hyper-gradualism" and nor is that relevant the topic at hand.

On the phyla, We are not discussing the posited evolutionary lines, per se...at least on this point, that theorically occured from the phyla that appeared in the Cambrian explosion or existed then, but why the same process that produced those phyla did not continue to do so for the next 500 million years.I do not expect exact duplications to occur, but I do think it's unreasonable to claim the process was on-going when no new phyla have appeared in over 500 million years.Hope that clears the issue up some for you. Just because the existing phyla, according to evos, kept evolving does not explain why there would not be new phyla appearing.

I consider all Darwinian methods "gradualistic", but PE advocates contrast their theory with "gradualism" and so I refer to the old notion that species as a whole slowly evolve into new species as hyper-gradualism.My understanding is most evos have moved away from thinking whole species evolve, but argue that sub-groups separate and evolve.

Or it never existed in the first place, but for sake of argument, let's take this further. Why would there not be ancestral populations similar to the first that arose and split into the phyla, which appears to be what you are arguing. Certainly, there was a niche or it wouldn't have evolved in the first place, and it is extinct, that niche is available, right? Hmmm....but there is a rule according to evos. The rule is Darwinian evolution. All things have heritable change and so over geologic time, it doesn't make sense not to see more evolutionary change laterally so to speak rather than just linearly. 500 million years is a very long time for new phyla not to emerge, or other new forms.What the evidence suggests, IF one assumes common descent, is that evolutionary pathways are prescribed, and moreover, once there is a burst of evolution within a range of organisms, that's it. They spent their wad so to speak.This is totally inconsistent with Darwinian evolution, however. The picture the facts create ASSUMING common descent (not saying that assumption is corrent mind you) is very different from what Darwinian evolution depicts.In that regard, men like Grasse and Davison are correct in stating that evolution appears to be a great process that occured via an unknown mechanism that is largely winding down or not occuring today.

I've read through this thread in it's entirety and have a couple of questions.We have situations currently where an ancestor group splits into very distinct descendant groups - fish vs. mammals for example. Some of the mammals have since evolved features that are typically found only in the fish population (killer whales for example).If science had decided to separate two phylum based on these features, then we would have exactly what rand is looking for, would we not?Is the reason why we don't see what rand is asking for that science, when defining the different high level classification groups specifically chose traits that have not re-evolved due to convergent evolution in order to simplify the classification scheme?

There are two ways it might happen. Cladogenesis and Anagenesis. Anagenesis is sometimes referred to as gradual evolution and yes it does occur and no, 'evos' have not moved away from thinking that anagenesis occurs.

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When enough mutations reach fixation in a population to significantly differentiate from an ancestral population, a new species name may be assigned. A key point is that the entire population is different from the ancestral population such that the ancestral population can be considered extinct.

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(wiki)If a new group diverges from A called B we might call that cladogenesis.If A proceeds to evolve away from its ancestral population we might say that anagenesis has occurred and the current population should be called C.If A splits into B and C then what happens to A? It either continues splitting cladogenesis style, evolves away from its ancestral population anagenesis style or it goes extinct.Since we know there are no ancestral populations hanging around, we know that the continuing splitting of the of the ancestral metazoa population into animal phyla cannot continue. Either the ancestral population went extinct or it itself evolved to such a degree away from its starting to point that it warranted being called a new phylum.

Or it did exist but it wasn't ancestral it was actually a descendant gone back in time to father itself. That isn't evolution as it is understand by science though, which is what I was describing. There were ancestral populations similar to the first that arose and split into phyla. I have no idea why there wouldn't be, without resorting to crazy nonsense. It might be extinct because the niche no longer existed, or there was something more fit competing for that niche. Niches change over time depending on the environment and the environment includes other life which changes with time partially because niches are changing over time as a partial result of life changing over time. That isn't a rule, it is a theory. There is nothing within the theory which demands that backbones cannot evolve multiple times. There is historical evidence that they didn't (well, I mentioned another possible evolution of notochords but let's not get complicated). The reason new phyla don't emerge has been explained. I don't feel like repeating it everytime you repeat yourself.