Talk:Cambrian explosion/Archive 2

message: As per to do list -  I have some stuff I can put here when I have a moment!
Grahbudd 07:00, 25 January 2007 (UTC)
thread_title: Pictures and refs

message: I've replaced Graham's timeline with a wikified one that's easier to read on the page (and a bit more colourful). I've also amended a couple of the dates where new data has allowed their refinement.
Verisimilus 18:03, 10 March 2007 (UTC)
replies: text: Done. For future reference, the timeline is editable at Cambrian_explosion/Timeline.Verisimilus 10:02, 14 March 2007 (UTC)
thread_title:  Timeline / Nature review 

message: Body ridges are a common feature in organism fossils 
 of the period, suggesting possible external food intake.
This doesn't sit too comfortably with me... there are many other possible reasons for ridges (e.g. gas exchange, structural support, artefacts of segmentation, hydrodynamics?) that don't fit this hypothesis; indeed other animals (trilobites, earthworms) are 'ridged' whilst not having this mode of life. I'm not convinced this is factual enough to be considered Encyclopædic content... whilst there is one prevailing view that they did have this mode of life I don't think a ridged appearance is necessarily evidence for it. 
Verisimilus 21:09, 15 March 2007 (UTC)
thread_title:  Dickinsonia ridges 

message: Alternatively, some new form of microbial or viral 
 infection agent may have developed which could 
 transfer genes between species, speeding up
 evolution by "sharing" useful features. This is 
 somewhat comparable to the Recombinant DNA
 process in sexual reproduction, but on a cross-species
 level.
After a quick search I can't find anything in the literature (or even in the link supplied) that suggests this hypothesis is anything more than an interesting but entirely unsupported and loosely defined conjecture...  Hence I don't feel it should be included here as 'encyclopaedic content' unless a reliable source is found.
Verisimilus 13:21, 5 April 2007 (UTC)
thread_title:  Viral hypothesis 

message: The structure of the article could be improved considerably.  The "Dating the Cambrian" section serves little purpose; that topic is covered throughout the article, and what is not could be merged into the "Significance of the explosion" section.  I also suggest putting the history section immediately after the intro, before the Significance section.  Also, "Timing of the Cambrian Explosion" seems to be more or less dealing with the same issues as "Causes of the Cambrian Explosion".  I would suggest removing the causes section from "Significance of the data" and putting it in it's own top-level section, and using a trimmed-down version of the timing section as an intro to the causes section.--ragesoss 23:55, 19 April 2007 (UTC)
thread_title: Structure of the article

message: It's quite a challenging set of demands, which I mainly agree with in principle. The balance I think that needs to be struck is one between an article that is concise enough to be readable without the attention wandering, and yet in depth enough to capture the imagination. One could argue that to discuss the Ediacaran biota at length would be to stray unnecessarily from the subject - and one could argue that the interested will follow the 'bluebird' whilst the uninterested will not be distracted from the main flow of article. 
Regarding the levels of 'in depthness' - I agree with this in principle, but it would be quite difficult to fit into the current article, which has several distinct sections. I feel that to a degree the article already does mention points in brief before expanding on them; but there could well be scope for improvement.
I'd wholeheartedly encourage you to have a dabble with the article, if you feel able!
| VerisimilusT 09:54, 21 April 2007 (UTC)
thread_title: Thanks for your comments

message: First off, VerisimilusT, thank you for your very gracious response.  You took it better than I hoped (and I was frustrated when I wrote it), this was a post I was a little bit worried about, so thank you for your thoughtful response.  However, I cannot take you up on your generous offer.  I do not feel at this time I have the kind of readable writing style that will be acceptable to the majority of wiki users (people will be editing out what I think are my best parts and it will just drive me crazy), and besides that, I don’t feel I know enough about evolution!  What I do hope is that I will be appreciated as someone on the other side, because it sure seems like everyone and their brother wants more formality in the writing.  More formality?  I ask, why can’t we explain it in plain English and introduce the occasional technical term that sincerely advances understanding?  I think we can.
Okay, as an example, take Thomas Kuhn’s THE STRUCTURE OF SCIENTIFIC REVOLUTIONS.  We could give a good meaty description in four sentences.  And not a baby description, but a good description for a college audience.  Four sentences.  And I think that good description would have zero or maybe one technical terms.  The technical terms are not what’s paramount.  It’s explaining it to someone just as smart as you are (you’ve got to give your reader that respect), but just someone who doesn’t happen to know this particular area.  
Okay, the Ediacaran animals, and the picture looks kind of like a sand dollar, but with lines radiating out from near center.  Alright.  Well, to an order of approproximation, all species are extinct.  Appropriately 99% of all species that have ever lived are extinct.  And evolution is bushy.  Looking backwards, you can see a main line.  But at any particular time, it’s bushy and going in all kinds of different directions and you have no way of knowing what’s going to end up being the future main line.  So, it would be no great surprise if the Ediacarans had gone extinct.   FriendlyRiverOtter 09:39, 27 April 2007 (UTC)
thread_title: More Judicious Use of Technical Terms

message: I'd have to disagree heartily on your 'main line' point. Evolution is indeed 'bushy', and just like a bush, there is no 'main line' - just twigs and twigs. It's popular - and easy - for humans to think that all evolution was directed towards them, but that's not how it works - things 'devolve' as fast as they 'evolve', and 'progress' can only be defined and measured by us, it's not an inherent property of the system. Evolution is change, and it takes us to decide when to call it 'progress'...
Re. the 'not unlikely' extinction of the Ediacarans: Species could be thought of as being a little like needles on a pine tree. It's not a perfect analogy, but an extinction of an entire clade would be like removing every single pine needle from an entire bough - if just one remains, the clade remains extant (i.e. non-extinct). Other, better documented mass extinctions have hit the pine tree like a strong wind - needles have fallen largely at random, and whilst sometimes one branch is decimated more than another, a major bough being completely stripped is incredibly rare. Twigs may be stripped (and go extinct), but larger boughs would always keep a few needles...
I suppose the counter-argument would go that the branches were twiggier back in those early days. Most people expect the 'Ediacarans' to be a major bough on the tree, but maybe at the time this was no bigger a branch than the trilobites', which went extinct at the end of the Permian... | Verisimilus T 12:26, 27 April 2007 (UTC)
thread_title: A 'main line' in evolution?

message: At the beginning of the Ediacaran, the sideshoots are going to be awfully close to the trunk as you say, and it’s going to be awfully hard to tell between them and the trunk itself.  Some of the sideshoots will develop into big bushy branches, but still, isn’t the default for any particular early species is that it’s more likely to be a sideshoot than an ancestor of a later species, isn’t evolution is that bushy?  
As I understand it, species are coming and going all the time, and the average lifespan for a new species, within an order of magnitude, is approximately 10 million years?
Thank you for the part about oxygen levels.  That’s exactly the kind of thing I need to start learning (oxygen first building up to a higher level, then stablizing at a more medium level, along with, I’m sure, a lot of bumps along the way).  I know the feedback mechanisms of ecology can be very complex, and with a lot of different feedback mechanisms going on at the same time.  So, I embrace the complexity (I mean, what else can I do!).
Now, I understand that sometimes (certainly not always) life is most bushy during the middle stages of colonizing a new ecological niche, and becomes less so as one or several species becomes dominant.  An example of this might be the evolution of horses.  And another example might be the evolution of us humans.  At the time of Australopithecus and as one species was evolving toward (through intermediary first?) Homo habilis, there may have been half a dozen species living at the same time (Australopithecus africanus  .  .  .  afarensis  .  .  .  boisei  .  .  .  robustus  .  .  .  and probably several other cool ones as well).  And considerably later on, we and the neaderthals were two branches.  We did not have the relationship of ancestor-descendant, but rather of cousins.  We both evolved from Homo erectus.  (Arguably, one of the saddest things parts of evolution is that our cousins the neanderthals are no longer here.) 
And to keep all this in time perspective, this is the last (approximately) 3 million years of human evolution compared to the 542 million years since the Cambrian Explosion.   FriendlyRiverOtter 02:45, 8 May 2007 (UTC)
thread_title: Life most bushy during middle stages of new niches?

message: The best visible example might be beetles.  Beetles have radiated in many and sundry directions,  many, many thousands of species, running into the hundreds of thousands.  And yet, it’s not really a question of “progressing.”  The different species of beetles are merely different.  
And on the microscopic scale, bacteria do the same thing to an even greater extent.
And as far as familiar animals, okay, how about Darwin’s finches?  Most probably, the branch started with a single species from the South American mainland, and from there bushed out with different species on different islands and in different niches  .
Or, how about the carnivorous mammal that was the ancestor of whales?  And from this one species, life bushed out to a number of species, with two main branches, the toothed whales and the baleen whales.
Of course, with the exception of bacteria, the Cambrian period was before all of this.  The animals of the Cambrian are less familiar, so we’re going to need to take more time in description and be more generous with photographs.   FriendlyRiverOtter 00:29, 21 May 2007 (UTC)
thread_title: Possible additional examples of bushiness.

message: From the timeline at the beginning of our article, the Burgess Shale fossilizations happened approximately 505 million years ago, which is thirty-seven million years after the start of the Cambrian.  That’s something that needs to be pointed out, because sometimes the Burgess Shale is so emphasized that it feels like it happened at the beginning.  And it didn’t. 
And, regarding our topic of life being bushy, I have long heard that a number of creatures found in the Burgess Shale were unique, never to be seen again, including having bodily architecture different from all other animals that have ever walked, creeped, crawled, or swum about the Earth.  Now, frankly, looking at the photos of the fossils, that’s not immediately obvious to me.  But I am willing to listen to arguments and perhaps become convinced.  For example, there’s a little creature that looks like a worm with spines.  Okay, it’s interesting.  If I saw a creature like that swimming in a pond today it would certainly get my attention, but I’m not entirely convinced that it has a unique bodily architecture.  
What I do understand is that one species of worm—with the three bodily layers of ectoderm, mesoderm, and endoderm—became the blueprint for many, many later animals (including all the familiar ones!).   FriendlyRiverOtter 05:28, 29 May 2007 (UTC)
thread_title: Burgess Shale some 30-odd million years AFTER start of Cambrian

message: Does learning on a Dvorak keyboard slow you down and get in your way when you are later trying to learn on a regular Qwerty keyboard, or vice versa?  No, studies have been done and it’s just the opposite.  Learning on either keyboard helps you if you later move to the other.  There is a positive transfer of learning.
I figure it’s probably the same with writing.  So, if one has spent time on the formal style most common on wikipedia, there will be positive transfer as one makes the transition to a more communicative style.  And I urge you all in fact to make the transition to a more communicative style!
Take a look at Richard Dawkins.  Or look at COSMOS (the book) by Carl Sagan, and compare it to any introductory astronomy textbook for that time period, or even for the following ten years.  I would suggest that it’s so much better in large part because Carl took the risk of being criticized.  He wrote in his own voice.  So if you do a good job of communicating with the interested lay person (and I hope that’s one of your prime audiences), you will probably be criticized as sounding too much like an essay or sounding too much like a magazine article.  Please take those as compliments!
Learn from good writers like Dawkins, but mainly find and develop your own voice.  For example, Richard uses the method of rephrasing something in different words.  This can be useful in that it kind of puts up an intellectual signpost and makes the terrain more understandable, but then he kind of overdoes it.  So, if you keep working on your writing and allowing your own unique voice to continue to develop, you might even become a better writer than Richard Dawkins.  How about that!  Please do not let any artificial constraints hold you back.   FriendlyRiverOtter 00:29, 21 May 2007 (UTC)
thread_title: All writing has positive transfer, including formal writing

message: I can't get the Ediacaran, as presented here, to match the Ediacaran biota tineline. which is right? Adam Cuerden talk 19:07, 28 June 2007 (UTC)
replies: text: Not quite sure what you mean. Both appear to end at 542Ma to me... I hope there's not a compatability problem with the template! Verisimilus T 19:39, 28 June 2007 (UTC)
replies: text: I mean some of the events in the Ediacaran. ~575mya seems far too late for the first Ediacarans, likewise, the "last global glaciation" seems excessively late. Adam Cuerden talk 21:05, 28 June 2007 (UTC)
replies: text: Ah. The "Global glaciations" on the Cambrian timeline refer to the Marinoan, which are poorly dated - between 570 and . And the first "Ediacaran fossils" refers to the first bona fide communities (rather than, e.g., the much-debated Twitya discs) - i.e. the Avalon assemblage. It's all very hazy down there - I think that this timeline has the right level of detail for this article, whilst the EB article needs to have more dubious finds mentioned. Although perhaps some clarification would be useful... Verisimilus T 21:31, 28 June 2007 (UTC)
replies: text: Ah, right. Fair enough. Just slightly confusing, as the Marinoan glaciations are linked to Snowball Earth (which talks solely about the Cryogenian) and so on. Adam Cuerden talk 23:24, 28 June 2007 (UTC)
thread_title:  Timeline 

message: Some private correspondence gave me the initial impression that this article needed major improvements in content, but after reading it twice I think the content is good (of course there's room for improvement in anything, and it will have to be updated to take account of new discoveries and analyses).
By far the largest difficulty is the article's academic vocabulary and style, which will put off non-specialist readers, who should be Wikipedia's target audience. So it needs lot of re-phrasing.
I also think minor re-structuring would help, for example:
*Intro as is. I disagree with one peer reviewer's suggestion that the intro should contain the difficulties the CE presents for Darwin's theory of evolution. The main reason for these difficulties is that Darwin's theory is gradualist, and it's probably  necessary to explain "gradualist", which would make this material too long for the intro.
*Theoretical significance as at present, plus explanation that Darwin's theory is gradualist.
*Difficulty of dating as at present but in much less academic language. I'd also check to see if the situation has improved recently.
*Difficulties of analysing fossils (and quote the Anomalocaris comedy of errors).
*Types of evidence - trace fossils; hard-part fossils; soft-part fossils from lagerstatten; molecular phylogeny. All in simple terms, with explanations of what they can tell us.
*Evidence from the Cambrian. I'd present this separately from and before pre-Cambrian content, because the Cambrian fossils explain the term "Cambrian explosion".
**Lack of pre-Cambrian metazoan fossils when the term "Cambrian explosion" was coined.
**Tommotian small shelly fauna.
**Sub-sections as appropriate on fossils from later stage of Cambrian. I'd check for all lagerstatten and especially to see what's come from China recently. Also check for evidence relating to organisms other than multi-celled animals (the intro currently mentions phytoplankton). Add images to illustrate some "wierd wonders" as preparation for the discussion of "riot of diversity" vs "acclerated normal evolution" (Hallucinigenia and 5-eyed Opabibia would be good).
*Pre-Cambrian evidence of multi-celled organisms. All discovered after the term "Cambrian explosion" became common in scientific usage.
**Body fossils
**Trace fossils
**Molecular phylogeny
::On second thoughts I may prefer:
::*Body fossils - pre-Cambrian and Cambrian. This gives the reader a more continuous chronology. It should appear before other types of evidence because: most paleontologists still treat body fossils as the primary source; it was body fossils that raised the apparent problem of the CE.
::*Trace fossils - pre-Cambrian and Cambrian.
::*Geochemical
::*Molecular phylogeny.
::*Phylogentic reconstruction (last because most speculative).Philcha 17:26, 19 July 2007 (UTC)
thread_title: Need to rephrase and slightly re-structure?

message: * What can DNA tell us about the cambrian explosion?  —Preceding unsigned comment added by Philcha (talk • contribs) 14:39, 3 December 2007 (UTC)
thread_title: Philcha's notes

message: I think that since I originally re-wrote this article, it has (inevitably) become more fractured in its viewpoints - ie it has steadily got less coherent.  This is not a trouble as long as the article still holds together - otherwise it will never make FA status - something that seems very distant right now.
When I re-wrote the article, I certainly and deliberately downplayed the "sensational" aspects of the CE, as typified by Gould's book, and still (apaprently) the majority view of popular understandings of the subject.  But this viewpoint only ever had limited purchase in academic study of the CE, and it is certainly completely obselete now.  Specifically: i) Things do not suddenly appear "explosively" except under the influence of taphonomic windows (ie the reason everything appears around Chengjiang time is preservational); but trace fossils and other information inform us pretty clearly that crown group bilaterians did not evolve until late Ediacaran time; ii) similarly, trace fossils do not "explosively appear" at the base of the Cambrian, but rather, diversify rapidly from latest Ediacaran time onwards ; iii) the whole debate between molecular clocks and the fossil record has almost collapsed as MC's have been adjusted to give dates close to that of the fossil record.
As fas as "bluebirding" goes: I am not sure exactly what this means, but I think that one of the things that needs to be corrected about the Cambrian Explosion is that we know everything about it.  In fact, almost every aspect of it is the subject of ongoing research; and it is right to reflect these uncertainties rather than present a misleadingly simplistic "solution" to whatever the problem is meant to be.  We do not know what the Ediacarians are: indeed, I would say that we have little clue at all.  We do not know if oxygen was important.  We do not know the phylogeny of most of the major groups involved, so this makes interpreting their fossil record problematic.  And so on.
A minor point: the dating of the lagerstätten in the text is inconsistent with the dating in the diagram.  The dating of the Sirius Passet is uncertain given that it is based on a Holmiid-like trilobite which is pretty dissimilar to the other holmiids: but if this is broadly right, then SP is probably end Atdabanian; and almost certainly considerably older than the age given in the diagram.  It could actually be considerably older than this, ie basal Atdabanian.  Chengjiang is, as far as I understand based on the brachiopods, probably early Botoman.
Dating the "speed" of the "explosion": this is highly constrained by the exceptional preservations.  All we know is that by Sirius Passet/Chengjiang time (c. 516 Ma or so), loads of stuff was around, and that in Doushantuo time (perhaps around 580-560??), nothing was.  In between we have increased diversity of small shellies and trace fossils, plus things like trilobites and echinoderms coming in at around 520 Ma.  I don't think one can pull out an arbitrary chunk of 10 million years from this interval and say that THAT was the "explosion"...  
Grahbudd 18:19, 19 July 2007 (UTC)
thread_title: A couple of comments

message: Just scanning through your additions, your "Why is it such a big issue" section, whilst a great addition to the article, may not stand up to close scientific scrutiny.
For starters, the analogy with the mammals - whilst interesting, and possibly helpful - is not without caveats. For example, it's recently become apparent that the mammals diverged long before the end of the Cretaceous, and the extent of the diversification may not be as large as it has been thought. (A little like the Cambrian, I suppose...)
::That's the point. A general reader will not know about the molecular phylogeny analyses, but needs to be told that rapid evolutionary radiations are fairly common. People with a strong interest in paleontology. like you and me, will know about the molecular phylogeny analyses and see the parallel.Philcha 10:21, 21 August 2007 (UTC)
replies: text: Once again, it's about the general reader and about the popular stereotypes with which general readers start. Yes, I will contest the "phyla appearing at once" view, which I never found convincing (it's too much like Saltation (biology), which is not credible in terms of morphological viability or population genetics). The real problem is how much one has to know in order to understand any analysis of the Cambrian explosion, which means the article has to start (over-)simple and increase the pace and intellectual intensity in a controlled manner.Philcha 10:21, 21 August 2007 (UTC)
thread_title:  Phlya 

message: I've already struggled with putting a length on the explosion, and decided against it, as per Grahbudd's comment above.  I'm not sure that it's helpful to pigeonhole time into "before and after the explosion". It was a smooth curve, and different definitions will cover different amounts of it...
:I understand the difficulties and objections, and I'll cover the different views and definitions. But the duration is the central point - did the 10 or so modern phyla which contribute most of the fossil record evolve from "blobs" in a time similar to or less than what it took for e.g. mammals to evolve from therapsids? If we already had fossil evidence that evolution from "blobs" (similar to porifera and / or cnidaria) to modern coelomate phyla took a few hundred M years, there would be no "explosion".
:I got the figures from reading around, and will have to add the refs.Philcha 10:39, 21 August 2007 (UTC)
thread_title:  Duration 

message: The info bar appears corrupted, there seems to be code overtop of it.207.6.125.46 (talk) 22:59, 27 January 2008 (UTC)
replies: text: is awaiting updating to work with the new preprocessor. Someone is bound to fix it soon. Verisimilus T 00:12, 28 January 2008 (UTC)
thread_title:  Infobar on Right 

message: I've just removed a new section suggesting that "Although no direct evidence exists, a new kind of viral or microbial infection process is one possible route that genetic material may have taken in exchanges between early species."  As far as I am aware this idea doesn't have any evidence in its favour, nor support from the scientific community; I feel this article should restrict itself to scientifically supported ideas, as there are thousands of intriguing but un-testable ideas out there, and we can't reasonably expect to cover them all.  Comments in its defence are welcome!
Verisimilus T 09:20, 10 February 2008 (UTC)
thread_title:  Viral cause 

message: After reading through the article, at present I'm willing to remove:
*Section "Cryogenian glaciations"
*The reference to the Gaskiers glaciation in section "Doushantuo Formation".
*The reference to [[Namapoikia] in sections "Ediacaran organisms". But it's also mentioned in section "Doushantuo Formation", and the cited article refers (indirectly) to [[Namapoikia]. 
*Section "Change in carbon isotope ratios at Ediacaran-Cambrian boundary" - but some of the content would have to moved into section "Carbon isotope fluctuations" (within "Changes in the environment", within "Possible causes of the explosion").
After that I find it difficult to identify content that can be removed, since: the pre-Cambrian content shows that complex metazoans did not originate in the early Cambrian and their emergence was probably not sudden; the descriptions of early Cambrian animals illustrate the exceptionally high level  of disparity.
Of course I'm not best placed to be objective about this because I wrote most of it. Constructive comments and suggestions would be very welcome! Philcha (talk) 12:40, 21 February 2008 (UTC)
thread_title: Making the article shorter

message: I've reinstated this section. The idea is quite new (Jan 2008), and may get its own Wikipedia article in time. Meanwhile mentioning it briefly in this article will: (a) remind editors to check up on whether it gets enough scientific support and additional info to merit its own Wikipedia article; make the CE seem less surprising because there's evidence of another explosion. If the idea of an Avalon explosion survives scientific investigation, eventually someone will use the 2 explosions as the basis of some principle in evolutionary theory, then we can produce an article about that too (unless they are simply taken as examples of Valentine's "empty niches" theory and its consequence that explosions at each grade happen only once). Philcha (talk) 18:45, 28 March 2008 (UTC)
thread_title: An Avalon (Ediacaran) explosion?

message: I'm sure sure if this has been discussed previously, but the Definitions section seems a little misguided. The beauty of a hyperlinked encyclopedia is that a reader can instantly go to the article of an unfamiliar word. If the reader is unfamiliar with a word, such as phylum, they can go to the relevant article, fill in any gaps in their knowledge and then return. 
Ashmoo (talk) 13:26, 7 April 2008 (UTC)
replies: text: There's a Wikipedia guideline Wikipedia:Summary style that articles should be as self-sufficient as possible; it also makes the point that that diffferent readers want different levels of detail. The summary here aims to present all and only what readers need to know in order to understand the CE and why it's an important subject. The Coelom article is too techical and detailed for this purpose, and Triploblasty is a stub. The intro to the Phylum article is closer to what the CE article needs, but is still a bit detailed and does not make the point that the Linnean classicification has its problems, especially with long-extinct animals. Philcha (talk) 15:54, 8 April 2008 (UTC)
thread_title: Definitions section

message: Someone has recently added a section "Quantum Evolution":
::Quantum evolution is the theory that the emergence of primitive consciousness accelerated the course of evolution. Major evolutionary transitions are hypothesized to arrise when small populations—isolated and limited from gene flow—would fixate upon unusual gene combinations.
I can see a few things wrong with this:
*The article Quantum evolution explains that the idea is based on based mainly on genetic drift, and does not mention "the emergence of primitive consciousness".
*Quantum evolution's  originator, George Gaylord Simpson considered the idea "controversial and hypothetical".
*The section is not supported by any citations that provide evidence or arguments that Quantum Evolution is relevant to the Cambrian Explosion.
I will remove the section in about a week if those objections are not met. Philcha (talk) 18:07, 9 May 2008 (UTC)
replies: text: I was thinking of removing it myself.  I'd take it out for now, and insist on a reliable source being provided before it was reinserted (at a minimum). Smith609 Talk 20:16, 9 May 2008 (UTC)
replies: text: I suspect that the user intended to refer to Quantum evolution (alternative), which indeed seems to include a bit of the mysticism mentioned.  Anyhow, (s)he has not responded to the note fairly put on the user talk page; and I think a bit more argument will be needed to convince at least me that this indeed is a theory held by some scientists within the field.  Hence, I fully support the removal. JoergenB (talk) 20:09, 28 May 2008 (UTC)
thread_title: Quantum Evolution

message: I've removed these sections plus the stump of some old content about molecular phylogeny; this material had caused confusion because it was commented out. To make matters worse, the stupid doibot inserts HTML comments but is not smart enough to leave commented-out content alone, so it creates nested HTML comments and therefore a real dog's doo-doo. The last version containing the whole of the commented out material is  in case anyone wants to mine the old stuff for additional info. Philcha (talk) 12:08, 11 May 2008 (UTC)
thread_title: Removed "Conventional record" and "Exceptional preservation"