Talk:Saccorhytus

Primitive?

"Saccorhytus coronarius is the most primitive known species of the superphylum deuterostomes".

Unclear to me what the sources mean by primitive. Would 'oldest known' be factually accurate? Looking at the Wikipedia page for primitive it expressly states that the word primitive cannot apply to a species; strengthening my impression that the phrase made no sense.

– ASA-IRULE (talk) 05:58, 31 January 2017 (UTC)

According to The Free Dictionary, the first definition of the adjective form of primitive is something like "occuring in an early stage of development or evolution", so I think the usage in the original sources is valid, and it also alludes to the importance of the discovery; i.e., this is possibly a common ancestor to the previously-discovered deuterostomes. I think the Wikipedia page for "primitive" means that contemporary species cannot properly be called more primitive/advanced than each other because primitive relates to order (i.e., what came first) as opposed to "level of sophistication". But it should be OK to say that Homo erectus is more primitive than Homo sapiens because it appeared first on the evolutionary line (not because it's less "sophisticated").

However, "oldest known" is not incorrect, and I don't have a problem using it if it prevents some confusion. The importance of the discovery could be discussed explicitly in a different part of the article.

– TastyChikan (talk) 19:28, 31 January 2017 (UTC)

Over thirty years ago evolutionary biologists began deprecating the use of "primitive." Indeed, TastyChikan describes its technical use very well, but biologists realized that non-biologists were reading it to mean lower level of sophistication, less complex, or simple. All of which are incorrect. I agree that "oldest known" is the way to say it. Nick Beeson (talk) 21:51, 19 September 2020 (UTC)

References

Deuterostomia without anus ?

Can somebody explain how researchers decided to put it in the Deuterostomia without having a second "mouth" (anus) ? That's what 'Deutero-stomia' means. Thank you. — Preceding unsigned comment added by 91.212.132.35 (talk) 11:12, 1 February 2017 (UTC)

The researchers placed this animal in Deuterostomia due to its possession of openings around their bodies (their body cones) which they thought were related to similar-looking structures in vetulicolians, with their pharyngeal pores, and vetulocystids. A generally-accepted defining trait for deuterostomes is the possession of pharyngeal openings. As for its lack of an anus, it is possible that either that it is at an earlier stage of evolution that hadn't yet evolved a distinct anus, or that its lack of anus is a secondary loss with the true original deuterostome ancestor that lived before it having a one-way gut with both a distinct mouth and anus. Giant Blue Anteater (talk) 05:48, 2 February 2017 (UTC)

or that its lack of anus is a secondary loss with the true original deuterostome ancestor that lived before it having a one-way gut with both a distinct mouth and anus. I.e., the situation with brittle stars.--Mr Fink (talk) 14:23, 2 February 2017 (UTC)

Since in all Deuterostomes the blastopore appears first and always develops into the anus I'm a bit more puzzled as to why this proposed ancestral deuterostome would be described as having a mouth and lacking an anus rather than as having an anus and lacking a more mouth or more accurately not having a distinct mouth and anus. language describing it as a deuterostome which has a mouth but lacks an anus suggests a creature which develops an opening at the blastopore then closes it up in later development and then develops a mouth at a distinct location in keeping with the definition of a deuterostome. the article seems to be missing some information from the sources to explain why such language is used but unfortunately I lack access to the primary sources. Can anybody help improve the article by explaining this further in the article using additional sourced information?Zebulin (talk) 17:44, 3 February 2017 (UTC)

The article's Reference 3 is the Primary Source, being the original (and very recent) paper published on this organism: there are as yet no other sources that are not based on this paper (as far as I know). The original paper (a letter in Nature) should be accessible here:

http://www.nature.com/articles/nature21072.epdf?referrer_access_token=O7fr6S2uCrl0bSEaJoRfhtRgN0jAjWel9jnR3ZoTv0Oz0VvtJ3OoBhIW1AQ7Cw_oSd6iCVf7msxw6fhyZLzYDmGcrdwhwTwE9VuvaIh0-hffANoXxPBjgU-bVMuzO5lfnqH8wIm5zntid0qYiX8smFu4qQl-5n3RRRUjcennrHJvD76n8j3Ofdelp7QfNRFHz2mfF3e5GgBYIrKTf2IF7g%3D%3D&tracking_referrer=www.bbc.co.uk

Since this is a very ancient (540m-y-o) fossil, we have no way (as yet) of knowing the details of its development – Deuterostomes over 500 million years ago may not all have developed identically to living Deutorostomes: it may actually have had an anus, which has not yet been identified (or is simply not visible) in the (few and tiny) fossils so far examined; it may not have, in the same way that Protostomes (from which it presumably descends) do not, in which case it represents a "pre-anal" stage of Deutorostome evolution, but has been classified as a Deutorostome because of other common factors. This would be a little ironic in that deuterostomy would no longer be the diagnostic feature of Deuterostomes, but these things happen, just as it turned out that Dinosaurs weren't actually lizards. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 19:31, 4 February 2017 (UTC)

Haptic

This article said, "…which may have played a haptic role,…". But what sort of haptic role? "Haptic" means touch, so does the author of this phrase mean Haptic communication or Haptic perception. Or something else. I intend to read the original paper and see what they said. I will modify the article and this talk page section as soon as I do that. Nick Beeson (talk) 21:46, 19 September 2020 (UTC)

"Haptic" as it was used by the authors of the paper probably meant the ability to contact surfaces. I decided to word this part as "touching its surroundings and related functions." Giant Blue Anteater (talk) 22:40, 24 September 2020 (UTC)

Saccorhytus is an ecdysozoan - an extinct bodyplan

https://www.biorxiv.org/content/10.1101/2020.09.04.283960v1.full

Better preserved fossils were described and Saccorhytus turned out to be something completely different: a very derived ecdysozoan which probably secondarily lost anus due to miniaturization. Not an ancestor of any other known animals nor similar to any such ancestors, but an extinct bodyplan. Closest living relatives are probably loriciferans and kinorhynchs and less plausibly nematoids. It is an interesting animal but unfortunately it won′t tell us anything about evolution of any known modern and extict phylum. Thus Saccorhytus merely increased the disparity of Ecdysozoa clade. — Preceding unsigned comment added by 91.229.254.10 (talk) 17:56, 19 October 2020 (UTC)