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)

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)