Talk:Nectocaris

Size?

The article doesn't say anything about the size of this critter. It should be mentioned.--JyriL ^talk 17:29, 15 April 2007 (UTC)

Probably arthrtopod(ish) after all?

New analysis in press, see http://dx.doi.org/10.1111/j.1502-3931.2010.00253.x. Since the cephalopod claim is technically unsustainably POV now, I have de-POVed the other articles (as far as possible; Petalilium and Vetustovermis basically need to be written anew fron the ground up). After updating Nectocaris, check "what links here" and update those too. Dysmorodrepanis (talk) 02:24, 10 January 2011 (UTC)

Neither Petalilium nor Vestutovermis are mentioned in the rebuttal by Mazurek and Zatoń. Consequently, we cannot draw any conclusions about those genera without it being original research. --Stemonitis (talk) 11:52, 1 February 2011 (UTC)

Recent changes

In this edit, a number of changes were made. I think I disagree with them all.

• The first claim that "the reconstruction is a reconstruction of the living organism and is independent of its biological classification" is clearly false. The author's idea of what the organism is, phylogenetically, obviously affects their decisions in reconstructing an animal. That the two reconstructions differ so markedly is compelling evidence of that.

  The reconstruction is based solely on the fossil data. The first reconstruction was based on a single, poorly-preserved specimen, and could be improved based on the additional 91 specimens available to Smith & Caron. M&Z don't disagree with Smith & Caron's reconstruction, but rather on the interpretation of the features it displays. Martin (Smith609 – Talk) 14:27, 1 February 2011 (UTC)

• Using the {{cite doi}} citation is inconsistent with the remaining citation formatting, and is also incomplete. The page numbers are recorded wrongly, and author forenames are missing, for no very good reason. Using such templates is far from obligatory, and may not even be desirable.
• You cannot discuss the "previously-accepted model of cephalopod evolution" without there being a replacement. As far as I have read, no such alternative was provided. Conversely, the existing understanding is characterised tolerably well as the "established evolution of cephalopods".

  By "the established evolution of cephalopods", are you referring to Yochelson's 1973 model of evolution from the monoplacophoran Knightoconus, Dzik's 1981 model of evolution from a larval monoplacophoran, or Peel's 1991 model of evolution from a Yochelcionellid? On what grounds do you discount the replacement proposed (briefly) in Smith & Caron 2010? Martin (Smith609 – Talk) 14:27, 1 February 2011 (UTC)

• The wording "undermine" comes from the abstract of the Lethaia paper. It states "Here, we point out important issues that significantly weaken, not to say completely undermine, Smith & Caron’s interpretation." After de-couching this from scientific speak into layman's English, it means that they have completely undermined Smith & Caron's interpretation.

  It means that M&Z claim that they have undermined the interpretation. Smith & Caron have not agreed with this. Martin (Smith609 – Talk) 14:27, 1 February 2011 (UTC)

• Following the changes, the whole article gives far too much weight to the – frankly – now discredited cephalopod theory. By all accounts, it surprised the cephalopod community, and many many people disbelieved it (I included one link to a blog that makes this point, for instance). The whole point of my work here was to remove that bias by giving some information on the new analysis. Playing that down skews the whole article unacceptably.

  The blogosphere is not always the best yardstick for truth. No analysis has disagreed with the interpretation that Nectocaris is unsegmented, has camera-type eyes, and has internal gills. There is complete consensus that dinocaridids are segmented, have compound eyes, and have external gills. Let's try to present each case on its merits. Martin (Smith609 – Talk) 14:27, 1 February 2011 (UTC)

Thus, I have reverted the changes. --Stemonitis (talk) 14:10, 1 February 2011 (UTC)

Does anyone happen to have a copy of the Lethaia paper? I'd like to see it, but all I currently have access to is the abstract. Also, do we have any photographs of the fossil, itself? At the very least, we should avoid using any reconstructions for the taxobox, as either version lends undo weight, in my opinion.--Mr Fink (talk) 14:32, 1 February 2011 (UTC)

I'll send it to you; give me a minute. (Anyone else can email me for the same.) --Stemonitis (talk) 14:35, 1 February 2011 (UTC)

Photographs of the fossil available from links here. Martin (Smith609 – Talk) 14:37, 1 February 2011 (UTC)

Stem group?

The stem group is kind of confusing in the taxobox. The way it reads now is implying that cephalopods are some other critters stem group. I suppose the intended meaning is that Nectocaris is a stem cephalopod, but that is not what the taxobox says. If the taxobox is to use the "stem group" approach, one would either have to write an article on stem caphalopods to link to, or find a published name for the group (being a grade or not). Wouldn't "Molusca, incerta cedis" be more correct? Petter Bøckman (talk) 20:58, 13 June 2011 (UTC)

No; incertae sedis implies that the position of Nectocaris in the molluscs is unknown. It is not; according to Smith & Caron, it is more closely related to the cephalopods than any other mollusc. "In stem group of -> Cephalopoda" might be more literal, but to be honest the existing set-up seems unambiguous, if one is familiar with stem-group terminology. Granted, this might be unfamiliar to the layman... Martin (Smith609 – Talk) 01:10, 14 June 2011 (UTC)

Well, there's stem-groups really being a marginal term, but my main argument is that what the taxobox say and what it implied really is not matching. What it is now saying is that Cephalopoda is a stem group. You and I of course know this is nonsensical and looks for other ways of interpreting what is said, but that can hardly be expected by the general reader. I would go with "Group: Stem Cephalopoda" or perhaps "Proto Cephalopoda", and then link "stem/proto" to Crown group#Stem groups or (perhaps better) write a short article on stem cephalopods. Petter Bøckman (talk) 07:57, 14 June 2011 (UTC)

I agree, Cephalopoda is not a stem group. The taxobox should read Stem: Pancephalopoda or what have you. If there's no name for the total group containing crown cephalopods and everthing closer to them than other living mollusks, then... well, are you sure there isn't? MMartyniuk (talk) 13:41, 14 June 2011 (UTC)

The reason that stem group terminology is so useful is precisely that one doesn't have to keep inventing names every time someone finds a new stem-group fossil.

Has anyone checked what Smith & Caron use in their manuscript's systematic section? Martin (Smith609 – Talk) 14:15, 14 June 2011 (UTC)

They wrote:

"Phylum Mollusca

Stem Group Cephalopoda

Family Nectocarididae . . ."

Presumably that's where the "Stem Group" rank came from. If we do keep that contentious classification in the taxobox, I think it would make more sense to list the taxon as "stem group Cephalopoda" and the rank as Class or leave it unranked. Cephal-odd (talk) 13:50, 21 October 2012 (UTC)

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Plectronoceras

Since Plectronoceras is better known now (by the public and perhaps by academia), and as cephalopods seem to have arisen from gastropod-like ancestors, i suggest we reevaluate the sections talking about its relations with cephalopods, or at least mention that Plect is a competing idea for their ancestral species. Anthropophoca (talk) 05:07, 9 March 2020 (UTC)