Fossils - Exposing the Evolutionist slight-of-hand

Fred: Your fundamental premise is wrong. A simple google search for evolution invertebrate fossil yielded several thousand results. A quick perusal of the top 50 sites shows there's a LOT of invertebrate research going on - and all of it shows evolution in action. We could easily just email some of the researchers for their views, but I don't feel like doing your research for you...

To add some additional fuel to Mark's conclusion, the following:

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From Fred Williams "Exposing the Evolutionist’s Slight[sic]-of-Hand With the Fossil Record":

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In his book Evolution: A Theory in Crisis, Dr Michael Denton wrote: Because the soft biology of extinct groups can never be known with any certainty then obviously the status of even the most convincing intermediates is bound to be insecure.15

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Since you make a big deal about Dr. Pugliucci and Mesonychid, I thought you'd find Dr. Denton's newest book interesting. In "Nature's Destiny" (1996), Dr. Denton states:

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it is important to emphasize at the outset that the argument presented here is entirely consistent with the basic naturalistic assumption of modern science - that the cosmos is a seamless unity which can be comprehended ultimately in its entirety by human reason and in which all phenomena, including life and evolution and the origin of man, are ultimately explicable in terms of natural processes. This is an assumption which is entirely opposed to that of the so-called "special creationist school". According to special creationism, living organisms are not natural forms, whose origin and design were built into the laws of nature from the beginning, but rather contingent forms analogous in essence to human artifacts, the result of a series of supernatural acts, involving the suspension of natural law. Contrary to the creationist position, the whole argument presented here is critically dependent on the presumption of the unbroken continuity of the organic world - that is, on the reality of organic evolution and on the presumption that all living organisms on earth are natural forms in the profoundest sense of the word, no less natural than salt crystals, atoms, waterfalls, or galaxies. (from the introduction to Nature’s Destiny, page xvii-xviii).

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If you're going to claim that "new data" should be taken into consideration in the debate, my suggestion is that "Evolution: Theory in Crisis" has been superceded by the author and is no longer appropriate defense of creationism.

I'm not sure that's the case. Although the Ediacaran/Vendian fossilary is sketchy, the few places where decent numbers of fossils have been found indicate a fairly diverse group of sessile, mostly bilateral, soft-bodied organisms. The big problem appears to be that only a few of them seem representative of anything definitively ancestral to the early Cambrian (mostly algal microfossils and sponges). Right at the boundary there is a very rapid radiation of small shelly fauna and "worm" tracks. OTOH, there doesn't appear to be anything indicating large scale ecological release that may have caused this profusion of shelly critters. I think the apparent explosion in the late pre-Cambrian and early Cambrian is related more to the paucity of decent fossil sites for the period - the three PaulK mentioned are basically it. IOW, we're looking at an anomaly due to the record, not to the forms.Why was there a rapid radiation of shelly fauna? One possibility is we're looking at a re-population lag following a mass extinction event (the Vendian snowball hypothesis). Several of the Ediacara do appear to have the start of more rigid skeletons or reinforcement (especially the boundary-level Tommotian fossils). However, I think a combination of key innovation (like multicellularity and rigid skeletons) and adaptive radiation (exploitation of new niche possibilities based on the key innovations) rather than competition is the most likely reason behind the new profusion of different forms.I also think that we're confusing the "snapshot" nature of the early fossil beds (like the Ediacara site) with diversity/abundance. How many decent beds like Ediacara or Burgess or Tommotia have been found between the Late Riphean and Late Cambrian, say? I think we're extrapolating too much from too little data, honestly. We see the profusion of forms at Burgess, for instance, and proclaim that they must have arisen relatively quickly (a few million years at most). I'm not convinced we can make that claim without a much more fine-grained record of the period than we actually have.

The best reference I have for the slowly increasing evolutionary momentum, including a discussion of the SSF, is Valentine JW, Jablonski D, and Erwin DH, 1999, "Fossils, molecules and embryos: new perspectives on the Cambrian explosion", Development 126:851-859. It's a review article, so it references quite a few primary sources that indicate a slow starting but increasingly rapid diversification beginning around 570 mya and moving at a faster and faster pace until peaking in the Late Cambrian. Mineralized skeletons start coming in greater numbers at around 550 mya. The shelly fauna do appear rather abruptly in great profusion just after the boundary. However, you have to remember there's about a 13 my gap between the "end" of the Ediacara and the beginning of the Cambrian. About the only decent (trace) fossils from that period is the famous Treptichnus pedum, which has the signal honor of being the only known organism/lineage to have "lived" in the Proterozoic and "died" in the Phanerozoic.Hope that helps.

His argument is a tad misleading. The first thing that jumped out is the old "too many changes" argument. It is erroneous because it fails to take into consideration that changes in regulatory genes - not all genes - may be the only requirement. Most of what he appears to be discussing here are structural- or phenotype-type changes (i.e., "new cell types"), which are quite possible with changes in one or a very few hox genes, for instance. One of the microbiology folks here can probably provide a more detailed answer, but that would be the route I would take.

Okay, I came up with a couple of other references you can use. The first one, unfortunately, I don't have an on-line citation for. It was sent to me awhile ago, so all I have is the abstract and an (incomplete, IMO) reference. I'll copy it in toto:Grey et al, 2003. Neoproterozoic biotic diversification: Snowball Earth or aftermath of the Acraman impact? Geology: Vol. 31, No. 5, pp. 459—462. Although the key elements of the article deal with an argument for the Acraman metor impact as a mass extinction event that led to the rapid diversification during the Cambrian (like other mass extinction events, the survivors achieved ecological release when all those neat habitats and niches were suddenly vacant), what I find germane to your discussion is the fact that a major order or even class-level change occurred in plankton - going from one lifestyle and body plan represented by a very few species to a whole different lifestyle and body plan represented by some 57 new species. So much for all life appearing in the Cambrian - this radiation took place at the end of the Proterozoic (i.e., pre-Cambrian). Of course, your friend will simply dismiss it by saying, "Well, they're all still plankton.", thereby ignoring the implications of this diversification happening before the so-called explosion back in the days when there supposedly weren't any critters.Another major problem with your friend's arguments is a fundamental misunderstanding of what is meant by "phyla suddenly appearing in the Cambrian". He's either deliberately obfuscating or completely misunderstanding that statement. Consider: if we look at the critters in the "phylum" taxonomic level today, we're talking literally (in some cases) millions of distinct species. At the Proterozoic boundary, however, "phylum" may only comprise a few dozen or less species. IOW, his fallacy rests on claiming an equivalency between what a phylum consists of today and what a phylum consisted of way back when. Someone here will know the official term for this. The reality is that since phylum is simply a generic term for a basic body plan, critters are assigned to a phylum based on this criteria, and your creationist is neglecting the minor fact that some critter had to be the first. It'd be different if there was evidence that all the millions of modern species appeared suddenly in the Cambrian rather than a few hundred - many of which had precursors in the Proterozoic in spite of what the creationists claim. Which of course lends stupendous support to the whole "descent with modification" and diversification of life through evolution scenario.Glen Morton (*we are not worthy*) has a pretty good article on line that explains this "phylum level evolution", appropriately titled Phylum Level Evolution. Hopefully you'll get some good ammunition from there.Keep us posted.