Talk:Eurypterid

Edits
I've tweaked a few bits, may add a few more bits of detail later - trying to keep it basic enough to keep people interested while retaining everything factually correct. Will also update the list of eurypterids at some point, as it is terribly out of the date and the taxonomy has changed quite a lot. I happen to work on this group, and have some papers in press that, once published, will alter things further, and I shall update the page with any changes once they have been published.

Severan (talk) gg 29 January 2009 (UTC)

I'm amazed! I add a little to the eurypterid stub from my off-hand knowledge, intending to come back and add to it in a more scientific manner, and here a few hours later it's nearly all been filled in! Great! One quarrel though, "They also had a pair of pincers, known as chelicera." I do believe the pincers constitute pedipalps, not chelicerae (singular chelicera), which are more like mouthparts/fangs. I won't change it, though.

umm, '8 pairs of walking legs' ? i believe it's 4 pairs, 8 total. the thing is i remember entering 8 pairs, as a typographical error, and correcting it later.. so if that's still there, someone must be challenging it?

I am adding to the discussion:

Pedipalps like the ones in scorpions are homologous to the first pair of walking legs in Eurypterus. The chelicerae in scorpions are anterior to the pedipalps and smaller. In the case of scorpions both the chelicerae and the pedipalps have pincers (chelae), but in spiders for example, the pedipalps are non-chelate. In male spiders the pedipalp carries a spermatheca. In horseshoe crabs, and apparently in some eurypterids, the first pair of legs in males has a hook-like modified distal segment specialized for holding onto the female carapace during mating. Horshoe crabs have the same number of prosomal appendages as Eurypterids and scorpions (6), but the walking legs with the exception of the last pair are chelate. One has to specify "prosomal" appendages because these animals have also abdominal appendages (gills). It is tricky to be precise, and at the same time concise and plain-spoken.

Concerning the walking legs in eurypterids, the total number of prosomal appendages is always six, but the number of walking legs is variable, because some appendages are specialized for uses other than walking: swimming, grasping. Thus, Eurypterus and Pterygotus have four pairs of walking legs, one pair of swimming appendages or paddles, plus the chelicera with pincers at the front end. Stylonurus has five pairs of walking legs, plus the chelicera and Mixopterus and Megalograptus have two pairs of grasping appendages, two pairs of walking legs and one pair of swimming appendages plus the chelicera. Thanks for reading.

Manuel O. Diaz


 * Ah, I see. How strange, arthropod limbs seem quite interchangable (especially centipedes!) but... Many pictures I've seen of eurypterids had a smaller 'first pair of legs' right at the mouth, with the pincers further back than those (but still quite up front). Are we sure these pincers were right AT the mouth, making them chelicerae? I know I've seen arachnids with pincerlike chelicerae, but it's so odd... —Preceding unsigned comment added by 64.122.63.142 (talk) 17:44, 13 May 2008 (UTC)

Chelicerae

 * Harvestman Mouth.JPG

As mentioned, it varies. The holotype of the clade - Eurypterus had tiny chelicerae hidden near the mouthparts used for tearing food. In other species like the Pterygotus the chelicerae were massive and looked more like those from modern scorpions or spider crabs. Do note that chelicerae forms vary and ALL chelicerate arthropods have them (and conversely do not have antennae). They do not need to be tiny or close to the mouth, but they do need to be the first pair of legs. From primitive pincerlike ones in scoprions, eurypterids, pseudoscorpions and allies to the more modern fangs/jacknife chelicera of spiders. Eurypterid chelicerae were more like those to the right from an Opiliones (Harvestman).

A more detailed anatomy of the Eurypterus is seen here: http://www.palaeos.com/Invertebrates/Arthropods/Eurypterida/eurypt-morphology.gif

An also important thing to note, in Pterygotids, the chelicerae are massive. The 'pincers' are actually not pincers homologous to those found on scorpions. They are actually the chelicerae, homologous more to spider fangs and the tiny mouth claws of scorpions. To put it more clearly, these pincers of the Pterygotids were the FIRST pair of limbs and thus chelicerae, while the pincers of scorpions and pseudoscorpions arise from the second pair of limbs (they possess chelicerae as well, but theirs are tiny). Their function is for grasping prey but they can still be folded back towards the mouth to serve more like other chelicerae. - Obsidi ♠ n Soul  23:48, 5 November 2010 (UTC)

The most fearsome swimming predators of the Palaeozoic?
"Eurypterids were the most fearsome swimming predators of the Palaeozoic." Well, let's see -- "The largest [eurypterids], such as Pterygotus, reached 2 m or more in length ..." Compare with Placoderm fish such as Dunkleosteus, "around 8 to 10 m (27 to 33 feet) long", "scientists at the Field Museum of Natural History and the University of Chicago concluded that Dunkleosteus had the most powerful bite of any fish, well ahead of sharks, including the Great White. Dunkleosteus could concentrate a pressure of up to 8,000 pounds-force per square inch (55 megapascals) at the tip of its mouth, effectively placing Dunkleosteus in the league of Tyrannosaurus rex and modern crocodiles as having the most powerful known bite." -- 201.51.231.176 20:28, 6 March 2007 (UTC)


 * Well that might be true for a preserved specimen, in should be staed that of all fossilised species discovered so far.....etc. As you know not all species are preserved and there might have been bigger, meaner, nasties things alive back then. But you are generally correct. I think the statement comes from the show, 'Walking with Sea Monsters''. Enlil Ninlil 03:53, 7 March 2007 (UTC)

Largest arthropods
I've replaced "Anomalocarids" with "Arthropleurids" in the first sentence, since the Anomalocarids were probably not true arthropods and were, in any event, probably less massive than either Pterygotus or Arthropleura, with much of the length of the biggest specimens being made up of the tail. PenguinJockey 20:22, 13 May 2007 (UTC)

Largest Arthropod?
There's some errors, i do believe Pterygotus wasn't the largest arthropod, it's rivaled by Arthropleura, which I think is larger. Just noting be more careful what you say. Ammonight423 00:50, 12 October 2007 (UTC)


 * Isnt there also Jeakilopterus and Agirocassis (even though it isnt a true arthropod I think) ScavengerR9 (talk) 13:52, 5 April 2022 (UTC)

Reading the physiology part of this article, the section ends by noting that the Horseshoe crab was once believed to be a close relative, but arachnids are now believed to be more closely related. In the very next section, on fossils, it asserts that the Horseshoe crab is the close relative. It either is, or it isn't, and it doesn't bear mentioning twice. I leave the actual edit to someone more informed on the subject. 24.136.171.150 (talk) 23:14, 17 November 2007 (UTC)


 * I've made an edit to straighten out the conflicts and redundancies. However, one problem remains. I'll give it it's own heading below. —Preceding unsigned comment added by 138.23.134.119 (talk) 00:03, 15 May 2009 (UTC)

thats one big bug!
http://news.yahoo.com/s/ap/20071121/ap_on_sc/biggest_bug_ever —Preceding unsigned comment added by 216.46.209.197 (talk) 02:38, 26 November 2007 (UTC)

List of eurypterids
Hmm... what are we going to do about this? I think the list in this article is better than the list I made, but I also think a list of Eurypterids deserves its own page. What are your thoughts? Abyssal leviathin (talk) 04:21, 21 December 2007 (UTC)
 * Your list is fine and is in line with other lists, if you wan't you can make a taxonomical list by cuting this one out. As the article expands it will need to be moved. Enlil Ninlil (talk) 05:03, 26 December 2007 (UTC)

Date of extinction
The eurypterids definitely went extinct at the P-T boundary. That was 251 mya. The header for the page, however, states that they lived until 248 mya. That's impossible if they went extinct at the P-T boundary; a 3 million year discrepancy might not seem like much, but plainly something is screwy here. 138.23.134.119 (talk) 00:05, 15 May 2009 (UTC)

Added to Body Plan
I added anatomically descriptive material from the TIP. I may go over the rest of the section to ensure accuracy and consistency.--Digthepast (talk) 07:50, 24 November 2009 (UTC)

Added List of Families and Genera
I added a list of Families and Genera, based on the TIP. Doubtless, a lot has occurred in this exciting field since 1955, including a reclassification of at least some, if not all, of the Hughmilleriidae. I do not have sources available to me for this, so if anyone has good source material for recent changes, by all means, please step up.--Digthepast (talk) 15:43, 29 November 2009 (UTC)
 * I have now added pages for the following eurypterid families: Pterygotidae, Eurypteridae, and Carcinosomatidae. Each page contains a description of the anatomical characteristics common to the family, and a list of member genera.  My plan is to continue with this.--Digthepast (talk) 04:19, 1 December 2009 (UTC)

Taxonomy
The intro says: "They are members of the extinct class Eurypterida (Chelicerata)." However, in the sidebox, Eurypterida is listed as their Order and Chelicerata as their Subphylum. I am not sure what to make of this. — Epastore (talk) 14:40, 26 December 2009 (UTC)

It is an order; I have changed the introduction accordingly -- instantn00dle 15:42, 15 November 2010 (UTC)

New Phylogeny section
I have added a phylogeny based on Tetlie's 2007 tree; it involved a lot of chucking out of little outgroups and the like to simplify it and ignoring most of the genus level classification. I hope everyones happy with it; I kept the notes next to the tree where they are easy to see although I guess this looks messy.-- instantn00dle 15:48, 15 November 2010 (UTC)

I think the phylogeny presented is unfairly biased towards Pterygotids, and ideally a more complete one will get uploaded eventually. Some of the 'minor' groups that got chucked out are actually the most important in terms of understanding the evolution of the group.

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Articles for eurypterid taxonomy, morphology, etc.
, I've been thinking in creating several articles that have other clades that could serve us and the readers to better understand the history and other things of eurypterids. For example, a template that contains all the genera grouped in their corresponding clades, like this one. While it can be done in the current template, that would widen the image a lot, probably not allowing an image to be placed. I have also thought about a "timeline of eurypterid research", like the same page applied to dromaeosaurids, or a eurypterid glossary, like this one (personally, I think this one is essential and useful, it would help us to link those rare words without an article). Do you agree? Do you have any suggestion? Super  Ψ   Dro  16:33, 27 August 2018 (UTC)
 * I'm not sure a template with every single genus is fully necessary but I could experiment a bit with how to make one that isn't overcrowded. A "Timeline of eurypterid research" is a very good idea, we'd have to start it out with a lot of stuff already in place, might be something to work on a bit before creating the article. I don't think we need a "Glossary of eurypterid terms", many of the anatomical terms used are not specific to eurypterids (maybe something like a "Glossary of chelicerate terms" would be better? I don't know) and as far as I know the most relevant terms are already discussed in this article pretty well and linking to the "morphology" section should work fine? Ichthyovenator (talk) 15:06, 29 August 2018 (UTC)
 * I think the chelicerate terms would be considerably more difficult but it could also be done. With the rest I agree. When would we start the timeline? Super   Ψ   Dro  17:23, 29 August 2018 (UTC)
 * Yeah, as I said I'm not sure a glossary article would be needed at all. We could start working on a timeline article straight away, maybe under one of our userpages. Ichthyovenator (talk) 17:44, 29 August 2018 (UTC)
 * I'm going to try to finish Strabops soon. I can not finish Paleomerus until they pass me a document. Afterwards, we can work in my sandbox. Super   Ψ   Dro  17:56, 29 August 2018 (UTC)
 * I preferred to publish the article first and work it there (link). Super   Ψ   Dro  15:31, 3 September 2018 (UTC)
 * Got it! I'll join in and help expand it in the coming days. Ichthyovenator (talk) 20:04, 3 September 2018 (UTC)

Renaming to Eurypterida
I think the title should be “Eurypterida” because “eurypterid” could refer to both Eurypterida or Eurypteridae, making it ambiguous  User:Dunkleosteus77 &#124;push to talk 02:58, 17 February 2019 (UTC)
 * Absolutely. This is yet another case of a misinterpretation of WP:COMMONNAME run amok. Official "common names" work (more or less) as article titles for extant bird and mammal species. Scientific names work better as article titles for almost all other taxa. Over the history of Wikipedia, WP:COMMONNAME has been misinterpreted to mean "avoid scientific names at all costs", on the grounds that "common names" are more RECOGNIZABLE than scientific names. Scientific names often meet WP:COMMONNAME's specification of the "name that is commonly used in reliable sources". Eurypterid is jargony shorthand for two scientific names; it is not a COMMONNAME in the sense of a recognizable vernacular name. It offers no RECOGNIZABILity benefits for general audience readers over the relevant scientific names. Plantdrew (talk) 06:25, 17 February 2019 (UTC)
 * Members of the group Eurypterida are referred to as "Eurypterids" in virtually every paper I've read on the subject, I'd argue that it's more than a "jargony shorthand" but I can see that some confusion might arise as a result of the family Eurypteridae (although I think "Eurypterid" almost exclusively is used to refer to the order rather than the family), renaming the article might be a worthwhile idea to consider. There's also the ever present idea of maybe using the more famous COMMONNAME, "sea scorpion", though the papers that comment on this seem to dissuade use of that name on the basis of being phylogenetically incorrect and confusing. Ichthyovenator (talk) 11:29, 17 February 2019 (UTC)
 * The Eurypteridae family is not widely used today, although it has had much prominence in the past for harboring a large number of genera and species in the past. Perhaps this page could be renamed to "sea scorpion" for the same reason that xiphosurids are called "horseshoe crabs" despite not being crabs. However, I would prefer to keep the current name. Super   Ψ   Dro  16:02, 23 February 2019 (UTC)
 * I would personally be in favor of either "Eurypterid" as it is now or "Eurypterida". As a family of only two genera (up until recently only one), I don't think there's many that associate "Eurypterid" more with Eurypteridae than Eurypterida. Would be good with more viewpoints though. Ichthyovenator (talk) 16:41, 23 February 2019 (UTC)

Fezouata eurypterids?
On the “Origins” section of the page, it says “There are also reports of even earlier fossil eurypterids in the Fezouata Biota of Late Tremadocian (Early Ordovician) age in Morocco, but these have yet to be thoroughly studied.” I presume this is referring to the undescribed fossil nicknamed “The Meathook”, which has been re-identified as being a probable hurdiid radiodont, close to Hurdia itself. 2.219.19.241 (talk) 10:30, 9 August 2023 (UTC)