Talk:Cambrian explosion/Archive 1

message: "has provided some of the best insights into this period of dramatic evolutionary change and experimentation that laid the foundation for most major modern animal body plans."
: Isn't this worded in a way that suggests evolution is planned and targeted? Which is highly disputable.
::No, the wording is pretty typical.--Quadalpha 06:45, 14 January 2006 (UTC)

message: "Thsi would be as if one were pacing off the length of a football field (starting 4 bya), when between paces 78 and 79 all the different phyla suddenly sprang into existence." -- I don't think this American football analogy helps at all here.  Could we find something more general?  Daen 17:02, 22 November 2005 (UTC)
replies: text: The 24-hour day analogy is often used, with a more universal image. --Wetman 23:59, 22 November 2005 (UTC)
replies: text: I've made this change. Hope my math is correct. 24.207.32.170 23:36, 14 December 2005 (UTC)
thread_title:  Football metaphor for phyla timeline 

message: Stuart Kaufmann has a theory that aspects of the Cambrian explosion can be explained by the mathematics of complexity theory. See Sole, R, P Fernandez and S. Kauffman, (2003) Adaptive walks in a gene network model of morphogenesis: insights for the Cambrian explosion. Int. J. Dev. Biol. 47,685-93. -- Scribelrus 09:41, 19 February 2006 (UTC)
thread_title:  Complexity theory 

message: An investigation in Nature  says that there are eleven inaccuracies in this article , although it does not specify what they are. I'm not knowledgeable enough to edit, but hopefully someone reading this is. 81.159.62.10 00:13, 15 December 2005 (UTC)
replies: text: I realize that the article has substantially changed since the Nature review.  However, we can't know for certain whether we've corrected the problems they identified, and for the time being (while we attempt to get more specific information from the Nature editors) it is safest to have an open admission of the potential problems.  Realize that a lot of people (including journalists) are going to be visiting this page soon, looking for precisely such an admission. —Steven G. Johnson 03:08, 15 December 2005 (UTC)
replies: text: Why am I reminded of those "What's wrong with this picture" pages in My Big Rainy-Day Fun Book? "Find seventeen mistakes in this picture" the editors challenged, and you drew a blue-crayon circle around the canary that was upside-down in its cage... --Wetman 00:10, 18 December 2005 (UTC)
thread_title:  Nature article 

message: I have restored the perhaps too rashly deleted text, which I wrote with care in order to replace the shopworn  "The idea of an "explosion" of life in the Cambrian period is still being debated", with a brief overview of the changing perspective. I've enclosed it (temporarily) within the rubrics text under review. I have also restored the suppressed reference to Steven Jay Gould's standard popular account, literally a prizewinner though intensely resented in some cobwebby corners. Now, let us begin to edit, not merely delete. Breathless verbalisms like "This period of evolution is source to some of the most unusual fossils ever recovered" transmit little solid information. Let's discuss the Cambrian explosion with the reader in mind. The last paragraph, for instance, is a good summing-up, but it's not enough unless it has been prepared for by some details, which I've restored. --Wetman 03:43, 15 December 2005 (UTC)
replies: text: Yeah, sorry about that, I started editting before you made those changes.  I removed Gould because the only reference to it sounded like we were shilling for his book.  If you have a better use for it, or just want to leave it in the references without a citation, I don't mind.  Dragons flight 03:47, 15 December 2005 (UTC)
thread_title: Review text

message: An article onm the Cambrian explosion that does not mention [[Stephen Jay Gould's  1989  Wonderful Life: , winner of The Aventis Prizes for Science Books in 1991, would be a caprice, perhaps just that of a couple of Wikipedia editors. Gould wrote about evolution so clearly, so publicly, so successfully, that he continues to be resented in some corners. --20:35, 17 December 2005 (UTC)
thread_title: ''[[Wonderful Life (book)|Wonderful Life]]''

message: One of the problems with this article is that specific facts have not been referenced. Also, why are we going against NPOV and saying that Gould's book is the best source for anything? I'm not saying it's not: however, as we all know, we don't take a stance on such matters. May I suggest we reword this to merely say that Gould wrote a book that is accessible to the layman? - 211.30.173.113 04:20, 18 December 2005 (UTC)
replies: text: If it's not the best, just name its two competitors, and we'll mention all three! Or perhaps there are other issues at work. If so, speak up! out with them! --Wetman 04:33, 18 December 2005 (UTC)
thread_title:  Problem 

message: I've attempted a rather comprehensive re-write of the CE article trying to bring into account rather more recent perspectives that have emerged from recent research on the subject.  this is by no means (AT ALL!) perfect, and needs references just for a start.  However, I hope it forms the basis of a useful discussion
Graham Budd
--Grahbudd 17:59, 21 December 2005 (UTC)
replies: text: Hi Graham.  I don't know what happened re: your effort to improve the article, but what you've written below seems a huge improvement on the current article.  Just for starters it introduces the idea that the "explosion" may not be real at all, and perhaps some sort of taphonomic artifact, etc. - the current article seems to omit this detail, along with many others.  Anyway, I'm all for you replacing the article with your text.  Regarding references, as I'm sure you've aware, the current issue of Phil. Trans. seems to be some sort of special issue on life around this time.  There's even a review of the explosion itself  that might be handy on this count.  Anyway, I really just wanted to try to get things rolling again re: your efforts.  Best regards, --Plumbago 09:24, 1 June 2006 (UTC)
thread_title:  New effort? 

message: At some point we have to address the fact that both creationists and proponenents of "intelligent design" claim the Cambrian Explosion, over and over, as supporting their respective positions.  I don't think it does, for several reasons that I think should be stressed in this article--and these are objective observations, not interpretations of the data.  First, molecular estimates aside there is ample fossil evidence of metazoan life before the Cambrian, with concrete evidence for at one modern phylum (Porifera) and pretty good evidence for at least a couple more (almost certainly Cnidaria, and possibly arthropods and some worm-like phyla).  Second, at least one phylum (Bryozoa) makes its first appearance in the fossil record well after the Cambrian explosion, and several other modern phyla have no fossil record at all, so it's impossible to say when they originated (although it's quite likely they date to the Cambrian).  But even though most of the phyla appeared in the Cambrian Explosion, in most cases their earliest representatives are nothing like any modern representatives of the same phyla (to the point that in many cases it's difficult to say with certainty just what phylum several Cambrian organisms belong in).  The assertion that "all phyla originated in the Cambrian explosion" conveniently overlooks the fact that a huge amount of evolutionary novelty appeared within those phyla well after the Cambrian explosion, and many well-known modern groups only appeared much later, e.g., insects and virtually all vertebrates.  Also, the phyla are frequently represented as appearing not only suddenly but completely unique and different from each other, whereas there is clear evidence that some phyla are more closely related to each other than to other phyla (e.g., the deuterostome phyla).  In fact these acknowledged relationships have at times resulted in certain phyla being split or lumped--that is, the definition of "phylum" is not as objective as we would all like to think--and if they are split you could indeed make the argument that several phyla did not appear until later.  The "body plan" definition of phyla is a highly subjective one.
Finally, the focus on the appearance of animal phyla in the Cambrian explosion overlooks plants, especially land plants, which have played an important part in the subsequent evolution of life; vascular plants appear well after the Cambrian, and flowering plants even later than that.  Discussions of the "Cambrian Explosion" tend to overemphasize those things that did appear (i.e., the earliest representatives of most metazoan phyla) while overlooking those things that did not appear (e.g., classes and other major groups within the phyla, plants, etc.)
There are many, many good websites dealing with the Cambrian Explosion and they should be linked here.  One excellent non-web reference is the book "On the Origin of Phyla" by James W. Valentine, which while not specifically about the Cambrian Explosion, has a wealth of information about the definitions, origins, relationships, and evolution of the phyla, all of which are pertinent to the  Cambrian Explosion. I would strongly recommend that anybody who intends to work on this article read this book first. MrDarwin 16:46, 7 January 2006 (UTC)
thread_title: Objective observations on the Cambrian "explosion"

message: The opening section seems to apologize for the slow progress of technology about a half-dozen times.  It should note ONCE that advances in technology have changed the picture, give a quick review of the old picture and then stick to the facts as currently understood. -- Pinktulip 14:07, 25 January 2006 (UTC)
thread_title:  To do: mention tech. only once 

message: The early Cambrian fossils coming out of Chengjiang, China merit a mention as they complement the Burgess Shale fossils nicely, but are about 10 million years older.  They certainly help give a more complete picture of the "Cambrian Explosion".  See Hou et al. 2004, "The Cambrian Fossils of Chengjiang, China: The Flowering of Early Animal Life" and also the website http://www.fossilmuseum.net/Fossil_Sites/Chengjiang.htm for an overview. There's a little bit of information already in the article Maotianshan shales, which could be linked. MrDarwin 20:52, 26 January 2006 (UTC)
thread_title:  Chengjiang fauna? 

message: This is truly one of the worst wikipedia articles I have read.  People who look up the topic "cambrian explosion" want to learn about it, not read an article that is 90% devoted to calling the whole thing a misnomer that has come about because of a lack of technology.  This article is SO one sided.  There have been literally thousands of authors who have written about the explosive development of life during the cambrian period.  And this articles has only the view of a handfull of cellular ichnologists who want to voice thier opinions and give no stage to other side of this issue.  This article seriously needs work.
:Agreed.  And does anyone feel the sentence "The Cambrian explosion continues to fascinate the non-specialist" is remarkably condescending?  NeighborTotoro 22:47, 27 August 2006 (UTC)
replies: text: Seconded.  As it happens, Graham Budd (I've forgotten their userid) wrote an alternative version, which you can see above.  It's much, much better than what we've got at the moment - not surprising as Graham's a researcher in this area.  Anyway, you might want to look that up and down to see what you think.  It's not perfect either, but it's a step forward IMHO.  Cheers, --Plumbago 09:51, 28 August 2006 (UTC)
thread_title:  This Article Needs Work 

message: Of the 20 or so metazoan phyla with extensive fossil records, at least 11 first appeared in the Cambrian. Of the remainder, one is known from the Precambrian and the other eight from the Phanerozoic eon (Collins 1994). An additional 12 soft-bodied phyla have poorly defined fossil records, many of which are conjectured to be Cambrian in origin.
Though this period is definitely of special significance in terms of rapid diversification and the emergence of new forms, some of that significance is likely to be overstated by the focus on macroscopic forms in the ways phyla are observed and defined. Molecular evidence suggests that at least six animal phyla had established themselves as distinct evolutionary paths during the Precambrian (Wang et al. 1999).
The large variety of fossil life forms found in the Burgess Shale, the much younger Maotianshan shales of China, and more than three dozen other Cambrian sites on every continent except Antarctica leads many researchers to doubt that 10 to 15 Ma is sufficiently long to explain the great diversity exhibited in the Cambrian fossil record. An emerging view is that the Cambrian explosion is the macroscopic conclusion to a prolonged period of evolution begun ca. 30 Ma earlier with the innovation of multicellular organisms.
The Cambrian explosion continues to fascinate the non-specialist. Stephen Jay Gould's Wonderful Life (1989) provides the best general account for the layman of the paleontological analysis of the Burgess Shale; the book was the 1991 winner of The Aventis Prizes for Science Books.
--Grahbudd 12:21, 2 September 2006 (UTC)
thread_title: Diversification

message: This article, before it goes to hard copy, should take into consideration the discovery of a microscopic bilateral metazoan, Vernanimalcula in the Doushantuo Formation, which with other work of the 1990s suggests that the Cambrian explosion is an apparent explosion— of large metazoans with easily fossilizable hard parts. --Wetman 05:23, 9 September 2006 (UTC)
thread_title: ''[[Vernanimalcula]]''

message: Hi, I've added a slightly longer reference to V. in the Proterozoic predecessors section.  I must admit that I am strongly of the opinion that this fossils is nothing more than a diagenetically overgrown blob with no affinities to the bilaterians at all.  Indeed, I published a response in Science with one of my colleagues to push this view when the original paper came out.  Despite the molecular date data (which in itself hardly gives a consistent picture, although it all tends to place the protostome-deuterostome split before the Cambrian), and the various stuff out of Duoshantuo, AND changing views of Ediacaran fossils. it is still hard to put one's hand on one's heart and say: "THIS is a Precambrian bilaterian!" without an act of faith being involved.  Still, I hope I have managed to maintain some sort of NPOV....Grahbudd 15:30, 13 September 2006 (UTC)
thread_title: ''[[Vernanimalcula]]'' Pt 2

message: Sunlight-created hydrogen peroxide could have been a factor. Geobiologists Solve "Catch-22 Problem" Concerning the Rise of Atmospheric Oxygen (SEWilco 05:35, 10 December 2006 (UTC)
replies: text: This is talking about a much much earlier period.  Dragons flight 06:12, 10 December 2006 (UTC)
replies: text: Wrong snowball.  Oops.  (SEWilco 16:19, 10 December 2006 (UTC)
thread_title:  Hydrogen peroxide factor 

message: The ext. reference
*Evidence and the Cambrian Explosion — ActionBioscience.org interview
was deleted by User:Woohookitty. It reads like a perfectly mainstream, though rather basic, explication of the Cambrian explosion and the kinds of evidence available, presented by Jeffrey S. Levinton, Ph.D., State University of New York, and including a useful series of responsible webite links. Is there a factor here that we ignore? This note is copied at User talk:Woohookitty.  --(Wetman 11:54, 14 January 2007 (UTC)
replies: text: User:Woohookitty responded at User talk:Wetman "I removed that link when I thought he was a spammer. If you want to reinstate it, be my guest." A look at the deleted contributions from new User:Scilit reveals over a hundred deleted links at science articles in the last two days. "Be my guest" is therefore something of a challenge.  --Wetman 12:16, 14 January 2007 (UTC)
thread_title: A deleted ext. reference