Talk:Chondrichthyes

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This article was the subject of a Wiki Education Foundation-supported course assignment, between 7 September 2020 and 11 December 2020. Further details are available on the course page. Student editor(s): GabbLarAnz.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 17:35, 16 January 2022 (UTC)

Untitled
The following was added by 200.1.19.70, which is in Chile: << There is a group on this subject in Chile more information on preyes@uach.cl >> Unclear how to access this. Is it an autoresponder? A mailing list? A finger address? The writer's personal box?

Fins
According to the National Audubon Society, Squaliformes can have either dorsal spines or an anal fin, but not both. This article says they can have dorsal spines, but never have anal fins. Tuf-Kat 09:25, Mar 4, 2004 (UTC)
 * Also seems to say that all of the animals in this class have the fins - see the uh, Appendages piece of this article for what fins. However, some of them don't have one or two of these fins, and so on, as it clearly says on the specific shark articles, and, in fact, on the list of sharks; I dunno about the rays and so on, though. Robin Talbot (talk) 17:51, 26 September 2008 (UTC)

Poor grammar
It seems to me that the grammar used in this article is somewhat subpar and should be cleaned up. Perhaps the article should even be rewritten entirely. What does everyone think?
 * I've had a bash at tidying it. Nurg 02:57, 10 September 2006 (UTC)

Taxonomy
Is Chondrichthyes still considered an official class? Fishbase, the Catalogue of Life, the Global Biodiversity Information Facility, all recognize the split into Elasmobranchii(sharks and rays) and Holocephali(chimaeras). I was just wondering if this taxonomic grouping is still up for debate or if a general consensus has been reached.

The age of Chondrichthyes
This article needs to state at approximately what time period and years ago this class emerged. That is if there's any information. þ 10:59, 27 July 2007 (UTC)
 * I hear before the Permian–Triassic extinction event, 70% of fish in the ocean were Chondrichthyes. Can anyone add information concerning that?

Endothermic or no?
Chondrichthyes, section "Metabolism" says: "Chondrichthyes are ectothermic or cold blooded, meaning they do not have to warm themselves through eating. Therefore, metabolism is slow as well as the fact that Chondrichthyes members do not have to eat as much."

Fish, section "Homeothermy" says: "... certain species of fish maintain elevated body temperatures to varying degrees.... All sharks in the family Lamnidae – shortfin mako, long fin mako, white, porbeagle, and salmon shark – are known to have the capacity for endothermy, and evidence suggests the trait exists in family Alopiidae (thresher sharks).... porbeagle sharks ... maintain body temperatures elevated in excess of 20 °C above ambient water temperatures. See also gigantothermy. Endothermy, though metabolically costly, is thought to provide advantages such as increased contractile force of muscles, higher rates of central nervous system processing, and higher rates of digestion."

We need to reconcile these. -- Writtenonsand (talk) 20:37, 31 May 2008 (UTC)
 * The fast answer is that the fish article got it entirely correct, while Chondrichthyes didn't. So yes, some sharks, notably members of Lamnidae, are capable of raising their temperature above that of their surroundings. 212.10.87.199 (talk) 01:06, 7 June 2008 (UTC)

m Eugnathostomata
The article links to "Eugnathostomata" (true jawed vertebrates) but that page has been deleted. Are there such things as true jawed vertebrates? It's very confusing for laypersons such as myself to find classifications that apparently don't exist

155.140.133.56 (talk) 17:54, 16 January 2013 (UTC)

Nervous system
This article lacks all mention of a brain, nervous system, or sensory organs, some of which are unique to it [the class]. Specifically, discussing the fairly well known "lateral lines" would be a good place to start.


 * I would like to add a bit of information about the structural similarities of myelin between chondrichthyes and tetrapods. Would it be appropriate to add it to this section? This is the reference I intend on using.  Cedombroski (talk) 22:58, 28 October 2018 (UTC)

Selachii redirect
I've edited selachii (which previously redirected here) to redirect to shark instead. I'm placing a note here because I suspect there are few if any watchers at selachii itself. If you agree with this change you may (or may not) want to make similar changes to selachian, selachians and/or selachoidei. It isn't obvious to me whether these are the same thing or not. My guess is that selachian and selachians should change to redirect to shark but selachoidei is different and should continue to redirect here. But that really is just a guess. TuxLibNit (talk) 21:40, 13 May 2014 (UTC)


 * I came here via Selachoidei and don't understand what it means. The article should mention it. 86.159.197.174 (talk) 21:58, 25 August 2014 (UTC)


 * For the record, I think a partial answer to the question above is that it literally means "group of shark-like things" and the remaining question is exactly which group is intended (taxonomies change over time, different taxonomies use different terms and the taxonomy currently used on wikipedia seems not to use the term at all). Based on various dictionaries (Merriam Webster online in particular) and the existing redirect on italian wikipedia from selachoidei to selachimorpha, I've decided to be bolder and redirect selachian, selachians and selachoidei to shark, as I think that is least likely to cause confusion.  That may not be enough to address the problem above, so I'll also start a thread at Talk:Province of Avellino (this is the only page that wikilinks Selachoidei), add Talk:Shark to my watchlist and see what (if anything) happens next.TuxLibNit (talk) 20:15, 29 August 2014 (UTC)

Coliodontiformes or Cochliodontiformes?
The "Taxonomy according to Joseph Nelson, 2006" lists extinct order Coliodontiformes under Holocephali. I'm pretty sure this is a typo as I find references to Cochliodont in older taxonomies with various suffixes but can't find Coliodont anywhere. However, I am wary of messing with this list when I don't have access to Nelson2006. TuxLibNit (talk) 19:42, 11 June 2014 (UTC)
 * I've never heard of "Coliodontiformes," I think it is a misspelling of Cochliodontiformes.--Mr Fink (talk) 20:44, 11 June 2014 (UTC)
 * You could also try checking to see if your local library has a interlibrary loan program, or see if Nelson's book can be accessible through WikiProject Resource Exchange/Resource Request--Mr Fink (talk) 20:50, 11 June 2014 (UTC)
 * Agree with the above, other holocephalan reference works list cochliodonts, not coliodonts (eg. Stahl, 1999) — Preceding unsigned comment added by 130.238.141.124 (talk) 11:09, 15 December 2014 (UTC)

Edits
The grammar needs to be fixed in the evolution section.

I would also add something about the jaw development in sharks

Mention elephant shark because it's a very close relative and it's genome is very important for research today.

Elephant sharks genome pertains to the evolution of Gnathostomes Venkatesh, B, A.P Lee, V Ravi, M.M Lian, Z.W Lim, B.-H Tay, S Tohari, A Tay, S Brenner, A.K Maurya, P.W Ingham, J.B Swann, T Boehm, Y Ohta, M.F Flajnik, Y Sutoh, M Kasahara, S Hoon, V Gangu, K.W Kong, S Ho, S.W Roy, M Irimia, V Korzh, I Kondrychyn, B Lorente-Galdos, J Quilez, T Marques-Bonet, B.J Raney, L.W Hillier, P Minx, R.K Wilson, and W.C Warren. "Elephant Shark Genome Provides Unique Insights into Gnathostome Evolution." Nature. 505.7482 (2014): 174-179. Print. — Preceding unsigned comment added by Przygodzki.1 (talk • contribs) 00:56, 1 October 2014 (UTC)


 * So if you are sure of your ground, be bold and make the changes you want to see. You won't break anything because it is easy to revert. If some other editor disagrees with what you have done, you can discuss it with them here on the talk page :) --Epipelagic (talk) 01:41, 1 October 2014 (UTC)

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The evolution of Chondrichthyes
The sources to section are poorly sited. The text states that the Chondrichthyes first appeared 395 million years ago, whilst it also says that Holocephali and Elasmoblanchii diverged 421 million years ago, 26 million years before that. This needs to be clarified. — Preceding unsigned comment added by Nils Horgby (talk • contribs) 08:28, 14 December 2018 (UTC)
 * I updated it and referenced it to reflect the earliest unequivocal chondrichthyid fossils are from 430 million years ago.--Mr Fink (talk) 16:00, 14 December 2018 (UTC)

pubioischiadic
To clarify, the edit summary here was supposed to read pubio- ---> pubo- ... almost certainly a typo, but sometimes the interface on this computer doesnt seem to populate the field properly. — Soap — 16:38, 25 May 2019 (UTC)

The paper on Helicoprion
The paper on Helicoprion, marked as a dead link, is at https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2013.0057 195.191.162.246 (talk) 06:13, 23 July 2021 (UTC)

Chondrichthys cladistics?
I think given we know so much about the clades within this class that we can only stand to benefit from added a cladogram to the page, what do you think?

•https://www.researchgate.net/figure/Chondricthyan-phylogeny-after-Coates-et-al-2018-1-Crown-group_fig2_343287266/amp ^ A possible source 좀비 브렌다 (talk) 06:44, 3 June 2022 (UTC)