nested heirarchies as evidence against darwinian evolution

Why?

So why wouldn't they continue to evolve new vertibrate (sic) phyla with some regularity over geologic time?

Mark writes:Any radically new bauplan that would warrant the status of phyla would then have to compete with already well adapted bauplans.

Are there any peer-reviewed studies that do that?

So what did that stop?

Frankly, I don't see why if new vertibrates (sic) and other new forms would not continually evolve.

wiki writes:The Cambrian explosion was a great flowering of life forms that occurred between roughly 530 and 520 million years ago;[4] during this time organisms similar to, but not strictly members of, modern phyla existed;[5] whilst some appear to be represented in the Ediacaran biota, it remains a matter of debate whether all phyla existed prior to the explosion.

Why would there not be new body-plans evolving forming new phyla from the same types of organisms? Did they spend their evo energy so to speak and so only the old lines can evolve?

Message 15 writes:So why not new major bauplans?

Message 40 writes:Why don't we see some plan with the complex nerves and say, a horizontal backbone or whatever the imagination can come up with, assuming a random process? If not that, then at least several or many new lines of vertebrates?

Message 46 writes:Why have they not evolved new major forms as they did before?

Message 49 writes:If invertebrates evolved into vertebrates, for example, over 500 million years ago, why hasn't that happened again and again?

Message 60 writes:Do we really think all the possible phyla evolved and shut the door on any new forms?

Hi Randman,It's been less than a day since you resumed participating in the discussion forums and already you're the number one moderator concern, primarily due to going off-topic, but you also managed to wander into violations of rules 4 and 5. You can't continue to participate here if you're going to so dependable a drain on moderator resources.To everyone else:If you want Randman to stay here, you can help by ignoring those portions of his posts that are off-topic, or by just noting that they're off-topic, as Molbiogirl has just done.

500 million years is a very long time for that process to end.

If you want to argue the same forms are crowded out, say, no new vertebrates could arise because the existing vertebrates crowded them out, fine.

However, the competition doesn't explain why new novel forms outside the current phyla would not emerge......why wouldn't, for example, we see all sorts of forms and phyla continuing to prop up from the original types of organisms that evolved the phyla in the first place?

There is a mechanism for planting trees and these trees form evolutionary phylogenies. If the mechanism is in place, wouldn't new trees be started, not just new branches, all the time?

Is the argument all the potential ways have been exhausted for those specific organisms and types of organisms leading to the animal phyla? So now, you cannot have any more evolution from that "stage"? That doesn't make sense if Darwinian evolution is how it occured (sic).

Moreover, that suggests evolution is limited by a preset existing range of plans.

I would like to see some evos address these points above I have raised. They are very specific and on target here.

Can we get to bottom of why the different viewpoints on this?

It has long been assumed that the extant bilaterian phyla generally have their origin in the Cambrian explosion, when they appear in an essentially modern form. Both these assumptions are questionable. A strict application of stem- and crown-group concepts to phyla shows that although the branching points of many clades may have occurred in the Early Cambrian or before, the appearance of the modern body plans was in most cases later: very few bilaterian phyla sensu stricto have demonstrable representatives in the earliest Cambrian. Given that the early branching points of major clades is an inevitable result of the geometry of clade diversification, the alleged phenomenon of phyla appearing early and remaining morphologically static is seen not to require particular explanation. Confusion in the definition of a phylum has thus led to attempts to explain (especially from a developmental perspective) a feature that is partly inevitable, partly illusory. We critically discuss models for Proterozoic diversification based on small body size, limited developmental capacity and poor preservation and cryptic habits, and show that the prospect of lineage diversification occurring early in the Proterozoic can be seen to be unlikely on grounds of both parsimony and functional morphology. Indeed, the combination of the body and trace fossil record demonstrates a progressive diversification through the end of the Proterozoic well into the Cambrian and beyond, a picture consistent with body plans being assembled during this time. Body-plan characters are likely to have been acquired monophyletically in the history of the bilaterians, and a model explaining the diversity in just one of them, the coelom, is presented. This analysis points to the requirement for a careful application of systematic methodology before explanations are sought for alleged patterns of constraint and flexibility.

Pay attention to the word "reappraisal."

The Ordovician period ended 443 million years ago, not 400 million years.

If you cannot show this, then please retract your statement.

Btw, this is a published explicitly ID paper.

... which also suggest their evolutionary appearance in the Precambrian.

Some of the oldest known fossils of these organisms are found in rocks ranging from 540-650 million years old corresponding to the Vendian (also called the Ediacaran Period), but the paucity of these fossils make their association with those of the Cambrian almost impossible, and the possibility exists that they are not even animals.

The Echiura fossilise poorly and the earliest known specimen is from the Upper Carboniferous (called the Pennsylvanian in North America).

One thing that seems to have evaded you is that if a phyla appeared in the PreCambrian, it did not appear post-Cambrian.

This suggests that at least six animal phyla originated deep in the Precambrian, more than 400 million years earlier than their first appearance in the fossil record.

The earliest body fossils that might represent Nematoda are of Early Carboniferous age.

We suggest that animal parasitism (nematodes) arose independently at least four times, and plant parasitism three times.

Why have no new animal phyla emerged in over 500 million years...

If you are going to cite molecular data, please realize that it places the emergence of all the phyla during or prior to the Cambrian era. It does not help your argument, but rather helps mine because my argument on this thread deals with why the phyla quit appearing.

Moving the discussion a bit forward, what I am trying to do here is to get people to take a good look at the picture from the data we have.

If you accept common descent and that's a big IF, what appears to be the case is you see at various stages, something as if there is pulse of for lack of a better term "evo-energy" infusing the process forward and then that stage doesn't repeat itself.

I'm beginning to see it as an artistic exercise.