Talk:Arthropod head problem

Diagrams

The fossil evidence and different theories of Cambrian arthropod head segmentation sections could really use some diagrams. --Savant13 (talk) 18:48, 2 May 2008 (UTC)

Reference to MADS-box genes in molecular development section

An edit (2, to be precise) by user MartinJ12033 at 07:05, 29 April 2008 and 07:07, 29 April 2008 inserted some language into the section on molecular development which is grammatically incorrect, refers to MADS-box genes - but talks about them in conjunction with sexual expression in plants - and is generally incomprehensible.

I'm not knowledgeable in this area; but since MartinJ12033 appears never to have made any other edits on Wikipedia, I doubt he will be available to ask him what he actually meant. Would anyone object to me changing that section back to its state before that edit? It hasn't changed since MartinJ12033's edit.

The version I can understand: "The arthropod head problem has been tackled in three main ways in this regard, first by using genetic segmental markers to probe the obscure region in front of the mouth, especially in insects; second by looking at Hox gene expression patterns to detect patterns of homology between different arthropods; and third, by studying gene expression in particular features (especially the labrum) to determine its appendiculate or other status."

The version I can't: "The arthropod head problem has been tackled in three main ways in this regard, first by using genetic segmental markers to probe the obscure region in front of the mouth, especially in insects; second by Hox gene, showing evidence of being evovled in the Paleozoic era, have the ability to express patterns of homology between different arthrods. Just as Hox genes express patterns, Mads-box genes have the potential to initiate an important role in the integration of sexual expression time pathways in plants." Third, by studying gene expression in particular features (especially the labrum) to determine its appendiculate or other status." —Preceding unsigned comment added by Peace Makes Plenty (talk • contribs) 12:02, 10 February 2009 (UTC)

The article is not clear

Although I read it through I couldn't understand what is the "Arthropod head problem" acctually. It should be clear from the first section and it isn't. Idvash (talk) 14:53, 7 February 2012 (UTC)

+1. ten years later I still can't figure out what the problem is supposed to be :( 90.155.34.28 (talk) 22:20, 19 April 2023 (UTC)

Outdated

The article is seriously out of date. Most of the references are dated before 2006 (ten years ago now); the main diagram introducing the problem is based on 2004 re-drawing of a 2000 original.

In particular, evidence is pretty conclusive now that there is no such clade as Tracheata – the phylogeny of extant arthropods groups insects with (actually inside) crustaceans, not with myriapods. This alters the nature of the "problem" and in particular any "solution". Peter coxhead (talk) 10:08, 19 June 2016 (UTC)

Very Outdated

There have been some recent papers on trilobites in regards to the head problem which could add some valuable information to this page. Also as people have said before, much of the page does not reflect modern cladistic groupings. In the coming days I will begin to update this page with the resources I can find. Reklaw27 (talk) 12:31, 6 september 2017 (UTC)

As you can see from my comment above, I agree that this page needs updating. It's been on my to-do list for some time, so I'll keep an eye on your work. Thanks for undertaking this! Peter coxhead (talk) 08:28, 7 September 2017 (UTC)

Reklaw27: it will be important to avoid relying on primary research sources for anything other than "X argued that xyz" type statements, as there are many conflicting points of view. Secondary (review) articles would be better, but with recent rapid change, old reviews may be of little use. It might be best to take a historical approach and to say '1900: A argued that abc', '1930: B argued that def', etc. Chiswick Chap (talk) 18:13, 8 September 2017 (UTC)

Diagram: no legs on thorax of Trilobite?

Do I read this diagram correctly and does it state that Trilobites do not have any appendages on their thorax? I don't have access to Invertebrate zoology, so I can't check the original diagram. BoH (talk) 22:21, 8 August 2019 (UTC)

@BoH: the diagram is misleadingly labelled, or perhaps more accurately, the terminology used for different groups of arthropods and by different authors is confusing. The non-shading and shading of the segments are exactly as per Ruppert, Fox & Barnes (2004) (which I have). However, their text says "Cephalization, or the development of an anterior tagma (head, cephalon, or cephalothorax) ..." So the unshaded part in the case of trilobitomorphs is, I think, what would be called the "cephalothorax" in other groups (e.g. arachnids). We need to see the original Ax source, which I don't have, to really understand the diagram. Later in Ruppert, Fox & Barnes (2004), they say that trilobites have 4 pairs of legs on their "cephalon", which isn't consistent with the diagram from Ax.

I'm not quite sure what to do about the diagram at present. Peter coxhead (talk) 08:15, 9 August 2019 (UTC)

Thanks for checking Ruppert, Fox & Barnes. Google Books doesn't show the page concerned from Ax unfortunately. But even if head should read head or cephalothorax, the pygidium also bears limbs. Anyone who may have access to Ax? BoH (talk) 14:34, 9 August 2019 (UTC)

Well, the diagram doesn't make sense, I agree. And it doesn't agree with the diagram below showing the operation of Hox genes. I'm inclined to remove it until this can be clarified. Thoughts? Peter coxhead (talk) 21:14, 9 August 2019 (UTC)

Removing it will probably lead to it never being corrected and never used again, so I would prefer an option to get someone with the knowledge on how to correct it. BoH (talk) 21:29, 9 August 2019 (UTC)