Talk:Rhyniophyte

Number of species

This page should say how many species of rhyniophytes there are. --Savant13 14:02, 21 December 2006 (UTC)

Devonian radiation?

The following paper gives the impression I'm familiar with that the radiation occurred during the late Silurian. Indeed, Cooksonia is a rhyniophyte, and is known from the Wenlock (Silurian).

Kenrick, P. (1997). "The origin and early evolution of plants on land" (PDF). Nature. 389 (6646): 33. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

I think the problem is that there are two meanings of "radiation" (1) diversification of clades (2) rise in numbers to achieve "dominance". While there is strong circumstantial evidence that the major vascular plant clades had evolved prior to the Devonian, there is little evidence they had risen to dominance.

In any case, Kenrick & Crane's book makes it clear that there are no known fossils of Rhyniophyta prior to the Devonian. They exclude Cooksonia from the Rhyniophyta because it is not a coherent taxon; many fossils of Cooksonia do not have vascular tissue, and none of them belong to the Rhyniophyta in their analysis of the fossils. --EncycloPetey 18:46, 7 November 2007 (UTC)

I see. I didn't have the book to hand but in the paper, they do include Cooksonia as a rhyniophyte; I'm pretty sure there are Siluian "rhyniophytes" but this may be an issue of semantics. As you say, I suppose the issue is what we decide to call a radiation. I've just been looking at a recent paper (below) which has an interesting graph of "mean axis diameter vs. time" which does seem to agree that a drastic stemmed-organism rise occurred in the Pragnian; it may be worth clarifying in the article that that's to what you refer. Verisimilus T 19:01, 7 November 2007 (UTC)

Clack, J. A. 2007. Devonian climate change, breathing, and the origin of the tetrapod stem group. Integrative and Comparative Biology 47, 510-523

When you say "stemmed-organism" do you mean taxa belonging to the "stem taxon" or "plants with stems"? Remember that recent studies (by Kenrick in particular) show that some of the fossils previously believed to be vascular plants are actually upright bryophytes that lack xylem (defined by having lignin and the mature wall patterning of xylem), and instead have hydroids (a conducting tissue known today only among bryophytes). --EncycloPetey 19:07, 7 November 2007 (UTC)

The graph shows a rapid increase in mean axis diameter during the Pragnian, which I'd taken to mean that plants with stems (but not necessarily vascularised stems) were becoming larger/more abundant. Thanks for pointing out the recent Kenrick work, that sounds worth reading; I'll take a look! Verisimilus T 09:17, 8 November 2007 (UTC)

"Class" rank in taxobox

As much as I know, Rhyniophytes are divided into three classes: Rhyniopsida, Zosterophytopsida and Horneophytopsida; so I am not sure if we should include "Classis" rank in the taxobox as it is included right now. Maybe we should make subpages for classes or smth? Klon-immortal 13:57, 8 November 2007 (UTC)

Please check the cited references (both by Kenrick & Crane) and other recent references. The Zosterophyllopsida and Horneophytopsida are not in the same clade. The zosterophylls are sister to the Lycopodiophyta and the Horneophytopsida are not vascular plants. The Rhyniophyta sensu Banks and others has been dismantled as a result of more careful morphological analysis of the fossils. So the Rhyniophyta classes are actually three clades in a paraphyletic basal assemblage of polysoprangiates. (See the cladogram on the Plant article.) --EncycloPetey 14:05, 8 November 2007 (UTC)

Image of Agalophyton

Hi,

I see that an image of Agalophyton has been added and removed from this article. Its overall morphology is similar to that of the Rhyniophytes; would it perhaps be better to include the image with a caption detailing the caveats, so that people unfamiliar with the topic at least get an idea of what the plant looked like?

Verisimilus T 15:52, 28 November 2007 (UTC)

No, because it doesn't belong to this group. That would be like adding a conifer picture to illustrate a page on angiosperms, or using an amphibian to illustrate an article on reptiles. Aglaophyton is a non-vascular plant; the rhyniophytes are vascular plants. --EncycloPetey (talk) 16:16, 28 November 2007 (UTC)

(Addendum) In any case, the recent reconstructions I've seen for Rhynia don't look like Aglaophyton at all. --EncycloPetey (talk) 16:50, 28 November 2007 (UTC)

Okay. My point was that you can't tell from the outer morphology whether or not a plant is vascular; in my hazy memory the two looked similar enough for the picture to be of passing help. Clearly not - thanks for clarifying! Verisimilus T 19:11, 28 November 2007 (UTC)

What mosses evolved from...?

We are tought in university that Rhyniophyta are ancestors not only of vascular plants, but of mosses too... We are tought that mosses evolved because of reduction of sporophyte and progress of gametophyte. As I see from the cladogram in this article, it's not true? Or it's not clear yet? Vikte (talk) 21:58, 29 March 2008 (UTC)

That hypothesis has been around for a long time, but it has not been supported by any research. All recent studies indicate that vascular plants are a monophyletic group, and the bryophytes are an ancestral assemblage from which the vascular plants evolved. There are no recent studies that support the evolution of bryophytes from a rhyniophyte ancestor. --EncycloPetey (talk) 22:26, 29 March 2008 (UTC)

Article title

As noted above, the original "Rhyniophyta" of Banks has been discredited; the Rhyniopsida are not within the Rhyniophyta in recent cladistic analyses. So (1) the article as of 29 Jan 2011 is out of date (2) the title is wrong: it would be better as Rhyniopsida with a brief comment on the former classification. I proposed to make these changes. Peter coxhead (talk) 17:28, 29 January 2011 (UTC)

Since I originally moved the article from "Rhyniophyta" to "Rhyniopsida", I thought I should comment on why I've now, after discussion with MisterCDE, moved it to "Rhyniophytina". The names, definitions and circumscriptions used for the group have not been clarified, as far as I can tell, in the last 7 years, so any article has to discuss all of them. The title under which this is done doesn't really matter. It seems best at present to use Banks's name, because although Cronquist et al.'s "Rhyniophyta" is slightly earlier, Banks's usage seems to have been the starting point for later work. An alternative could be to use the informal "Rhyniophyte", but this has also been used for the Rhynie flora, so is less clear. Peter coxhead (talk) 10:03, 14 March 2018 (UTC)

Problems with this article

This article quite confidently makes some assertions which really should be flagged as highly tentative in the present state of knowledge of these early plants. The article on Polysporangiophyte Taxonomy is far more circumspect.

I also think the "Partial cladogram by Crane, Herendeen & Friis 2004" shown here is somewhat misleading; in the paper cited, the name on the diagram is "Rhyniaceae" not "Rhyniopsida". Those authors do not use the term "Rhyniopsida" at all, as far as I can see.

I also have a problem with citing "Novíkov & Barabaš-Krasni (2015)" as an authoritative text in English wikipedia. This document is written in Ukrainian, which is hardly likely to be accessible to readers of the article.

Finally, I haven't been able to get my hands on any copy of Kryshtofovich's 1925 article in which he supposedly publishes the class name (albeit as an order, Rhyniales, so they say). Many botanists published very informal descriptions at that period, often on very meagre second-hand knowledge of the fossils, and unless the description satisfies certain requirements (quite minimal, it is true) this may not be a valid publication. Nevertheless, I have added the publication details so someone else may be able to see. Certainly, none of the references cited elsewhere in the article give any clue as to the acceptability of the name, they merely repeat it. MisterCDE (talk) 03:12, 19 February 2018 (UTC)

I agree that the article needs to be revised (but it could be said that I'm biassed since I created and wrote most of the Polysporangiophyte article. It would, I think, be better to have an article under some vaguer title like "Rhyniophyte" that is clear about the changes and uncertainties over the phylogeny of the plants that have been placed here. Peter coxhead (talk) 10:48, 20 February 2018 (UTC)

Yes, this article should be renamed to the more informal term, with redirects to it for the formal taxonomic equivalents. In fact, there seems to be a redirect already in place from Rhyniales to this article. But in addition to renaming it needs editing as well. Go for it, Peter! MisterCDE (talk) 04:04, 21 February 2018 (UTC)

Having had more time to review this article, I am even more concerned. The contents of the section titled "Taxonomy" I cannot find through Google in any other reference, apart from those created from this article. Certainly the taxonomy as shown is not from the cited references "Novíkov & Barabaš-Krasni (2015)" and the anonymous link "http://mave.tweakdsl.nl/tn/genera2.html" whatever that is (neither of these would be considered authoritative secondary sources). This taxonomy section appears to be original research, a mashup of the two references with additions from IFPNI. Also, Sciadophyton would not be considered a rhyniophyte nowadays, it has for many years been accepted as the gametophyte of a Zosterophyllum. Given the many different opinions about the taxonomy of these early plants, either all the different taxonomies are displayed (which I don't think is desirable for readability) or none. As suggested above, any formal botanical name needs to be taken out of the title, and the article rewritten completely to cover "rhyniophytoids" as plants of uncertain affinity. At the moment, it appears to jump from trying to describe a formal taxonomy, to duplicating stuff about the Rhynie chert which is covered elsewhere. MisterCDE (talk) 03:08, 2 March 2018 (UTC)

The article has now been fixed as follows:

• It was moved to Rhyniophytina from Rhyniopsida, because the former seems to be the more commonly used name and corresponds better to the informal term "rhyniophytes".
• It was then updated using material that User:MisterCDE had prepared at User:MisterCDE/sandbox.

Peter coxhead (talk) 10:15, 13 March 2018 (UTC)