The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
"immunity to predation", mentioned 3 times in the text: only, it's not true. Firstly, even adult elephants are hunted and killed by lions, and by tigers. Secondly, young (and sick) animals (such as juvenile giraffes) are regularly killed by multiple species of predators. The topic deserves more than 3 disorganized passing mentions; better would be a section which discusses this topic in detail. Done
Living long and reproducing slowly involves very serious the trade-offs, which include another major topic that gets much too brief a mention, k-selection. It takes a megaherbivore a very long time to grow its population... it's the opposite strategy to (say) that of Covid-19, where natural selection ensures that the fastest wins, big-time: which is only to say, the article needs to explain (and probably, to diagram) why being slow can be selected for, given that there is a race on. Done
This is only partly done, see "Second reading" below.
The Evolution section rightly mentions the Permian, the Cretaceous, and the Pleistocene, but names and illustrates only one species: and the name is only in an image caption, and not even wikilinked. This does not seem like due coverage of the main points (criterion 3a). The Evolution chapter needs a section on each of the three named periods, with an account of the major groups of megaherbivores in each period. That account should name at least a few of the key taxa, and illustrate them briefly. Done
This is only partly done, see "Second reading" below.
In that context (Permian-Cretaceous-Pleistocene-Recent), the chapter "Species" with its bold "This is a list of all nine extant species" looks radically misplaced, WP:UNDUE, or to put it another way, recentist and unbalanced, given that most of the world's megaherbivore species are extinct. Perhaps the best thing would be to move the whole list to a separate List of extant megaherbivores, and then discuss the "Recent" or "Extant" situation in the same amount of detail as each of the other 3 periods, with the same focus: phylogeny. Done
This is only partly done. The Pleistocene section at least has a little discussion and some illustration; the Permian and Cretaceous sections (the latter misnamed really, as 3 of its meagre 4 sentences are about the Paleogene, not the Cretaceous) really don't say much about the diversity of megafauna, or the reasons for the extinctions.
Missing, also, is at least a brief discussion of the parlous state of many more large herbivores (e.g. Ripple et al 2015). The question here would be, are the megaherbivores special in some way, or just the first signs of a much bigger extinction process that is still under way? There are several major Wikipedia articles to link to on this question (not to mention global warming). Done
This doesn't seem to have been done at all? What are the main extinction processes then? Where are the links? What is predicted to happen in the next centuries? Where are the citations? I don't see any of it yet.
Missing, too, is a reasonably detailed discussion of another very briefly mentioned but critically important fact, the Quaternary Extinction Event. "humans could be the causes": well, they could, and the arguments for and against need to be mentioned. Once again, this needs a section to itself, with a map (which would ideally show some numbers of species by continent, and dates). Done
That raises a more general topic, which is the multiple extinction events (for instance, Galetti et al 2018, but there are plenty of sources). You might want to discuss, for instance, whether megaherbivores are uniquely vulnerable to extinctions in geological time, or whether they're just more noticeable.
Awaited.
Also conspicuously missing is any account of the phylogeny of the megaherbivores (in each of the three periods mentioned, and for the modern/extant ones as well. It would be nice to illustrate the map by putting some images of extinct megaherbivores on each continent. If you'd like a hand with that, just ask. Done
The above comments indicate a fairly radical restructuring of the article. I do not actually think this will take very long, but it is evident that the current structure is ad hoc and inadequate. The key themes are evolution/phylogeny with the four key geological periods; and the whole question of the evolutionary trade-offs, basically, defeating predation with enormous size, at the cost of slow reproduction.
Given the reshaping that is required here, I will have to go over the article again once the main work to meet the above comments has been done.
Given the comments above, the image review will have to wait.
2nd pass: ok, all the images seem to be properly licensed on Commons.
What is the function of the two images in "Reproduction and longevity"? Neither image has a caption which in any way connects it to the section's text.
This article is not yet at the required level. If you'd like to indicate how much time you need, or alternatively if you get started and show steady progress, then I'll be happy to work with you to get the necessary changes into the article, and to offer whatever advice I can along the way. Chiswick Chap (talk) 17:32, 6 January 2024 (UTC)[reply]
It's mid-night over here, and I'm extremely tired. Will finish up later today. I could use your help with the images and maps, besides, I don't think research will be a problem. I believe it will take me about 5 hours to complete. 20 upper (talk) 22:13, 6 January 2024 (UTC)[reply]
Super. Let me know details of exactly what graphics you want, best on my talk page. Chiswick Chap (talk) 03:52, 7 January 2024 (UTC)[reply]
Chiswick Chap I'm mostly done, but I'm not sure about your 7th point. 20 upper (talk) 17:22, 7 January 2024 (UTC)[reply]
A trade-off is a process where something is gained at the price of something else, so an equilibrium is reached between competing evolutionary pressures. Sickle-cell anaemia is the classic evolutionary trade-off as the homozygous trait causes very serious disease, whereas the heterozygotes gain protection from malaria. The result in that case is polymorphism. Your megaherbivores have sacrificed rabbit-quick reproduction for *relative* immunity from predation; you've partly discussed the k-selection but without connecting it to the selective impact of predation. The point is that bigger = slower but safer, so r goes down but so does the death rate. Since the whole MH story is encapsulated here, you need to tell and cite this story. ATM the "Reproduction and longevity" section reads like one hand clapping, if you take my meaning. Chiswick Chap (talk) 17:34, 7 January 2024 (UTC)[reply]
Well, the article certainly looks and feels better than first time around. I note that several of the items have been marked "done" but are at best only partly addressed; one is not in fact done; and one hasn't been addressed.
I'm still concerned that the article is very light on theory, and that its coverage of "the main points" of evolutionary ecology as it affects megaherbivores remains questionable.
The link between low reproductive rate and long lifespan still doesn't seem to have been made: these are not isolated properties but necessarily connected, and that definitely doesn't come across in the evolutionary ecology argument. Done
As I mentioned in answer to your question in Summary above, the death rate (due to predation) has to be lower than the reproductive rate, or the megaherbivores must go extinct. The article needs to follow [1] Owen-Smith 1988 and explain this central connection of the two rates, and to state known rates of predation. On p. 293, Owen-Smith gives the fastest possible rate of population growth among elephants as 6 or 7% p.a., and among hippopotamuses some 10% p.a., pointing out that predation cannot be more than these rates or extinction would follow. This is a crucial point, certainly one of "the main points" and the article cannot pass without explaining it in detail. As I already said, this sort of thing is so important it should really be diagrammed as well as written. Done
A related point is stability, which Owen-Smith discusses. Megaherbivores are supposed to demonstrate stable populations because of their extreme K-strategy. Owen-Smith points out that given man's dire effects on Africa's megafauna in the past century (yeah, hunting, poaching, human population growth and encroachment on remaining habitat, the whole bit), stability is looking elusive (remnant populations, near extinction). But I see in the news this week that elephant populations in Southern Africa are at last levelling out. Done
What page is this? 20 upper (talk) 14:43, 8 January 2024 (UTC)[reply]
I think you need to borrow the book from the library, whether the Wiki one or your local.
@Chiswick Chap: I have the book; I borrowed it from my great-uncle, but it has stains on the pages, a torn cover, and several missing pages. I think Owen-Smith mentions stable populations in page 200, but I don't have that page. 20 upper (talk) 18:19, 8 January 2024 (UTC)[reply]
:-) Feel free to cite the chapter. Chiswick Chap (talk) 18:58, 8 January 2024 (UTC)[reply]
The whole extinction question is now at least mentioned, but only just. Again, it's extremely important, especially as there have been repeated mass extinctions; you have provided a few bare facts about the different events, but nothing about the principles, which could be said to be "the main points" here. Done
"Megaherbivores Modify Trophic Cascades" (Le Roux et al 2018). Seems like a major point in MH theory (whether right or wrong), and certainly needs to be argued through. Read the paper and write a section presenting the arguments.
I think I'm Done here, but what do you think?
I don't think you are anywhere near done with [9] Hyvärinen 2022 which discusses impacts of all sorts; and I doubt that the brief mention not affected by "the landscape of fear", and that they altered trophic cascades from [11] Le Roux 2018 will do more than mystify the average reader: they will wonder what such a landscape is, what a trophic cascade is, how a MH might alter such a thing, and go away completely unsatisfied, confused, and believing that the topic is too technical for them. The required level of explanation might be some talk about lions frightening small deer away from densely wooded areas where they can be approached without time to raise the alarm and run, while elephants can trample in there without concern: obviously you need to source what you say, but there's no point repeating the incomprehensible either. Done
Trimble eta al 2009 "elephants appear to respond [to limited resource availability] first through a reduction in reproductive rate ... likely due to the evolutionary significance of extremely large body size – an adaptation that increases survival rate but decreases reproductive potential. Other megaherbivores may respond similarly to resource limitation due to similarities in population dynamics." This again may be right or wrong - they present evidence for it - and it certainly looks like a key point for the article, to be discussed for (as just quoted) and against ("Eberhardt's paradigm"). Done
A small suggestion: rename "Reproduction and longevity" to "K-selection", and move the first paragraph of "Reproduction" above the "Reproduction" subheading, as the paragraph is about K-selection not reproduction. You could also delete the first sentence in "Lifespan and mortality" as it's a repetition.
Done.
Once again, I'll pause here, as what you write and cite will affect the review. Chiswick Chap (talk) 21:20, 7 January 2024 (UTC)[reply]
@Chiswick Chap: Please have a look now; I've been reading and working all day. 20 upper (talk) 21:29, 8 January 2024 (UTC)[reply]
Good work! It's looking very promising. If you could indicate on this page which items you feel you've completed, I can check and strike them off. Chiswick Chap (talk) 21:43, 8 January 2024 (UTC)[reply]
Now, this looks like a job for me. 20 upper (talk) 12:55, 8 January 2024 (UTC)[reply]
Sorry for disrupting; I just spotted some problems that I would like to write down here:
Megaherbivores are K-selected species and many other statements about biology and ecology: These only apply to mammals. For example, the opposite is the case for the largest megaherbivores that existed, the sauropods (these laid eggs and produced a lot of very small offspring). I think that extinct megaherbivores should be considered (and contrasted with modern megaherbivores) in all those sections, I don't see any reason why "megaherbivore" should be restricted to modern taxa. Indeed, the extinct ones are crucial for understanding the modern ones.Not done Explained below
I mainly agree with Jens here; if you want to say that MH including dinosaurs are K-selected, then we need a source to say so. Without one, the bare minimum is to say that dinosaur evolutionary biology and ecology may not have resembled that of mammalian MH; i.e. we should say up front "Mammalian MH ... " (in some form of words) for "Ecology", "Adaptations and size", "K-selection", as none of the sources used in those sections claim to apply to dinosaurs. Currently, the implication is that all the claims apply to both dinosaurs and mammals, which is entirely unverified by the sources cited (would fail GAN criteria 2b and 2c). Chiswick Chap (talk) 11:33, 10 January 2024 (UTC)[reply]
Explosive eruptions were the primary driver of the extinctions – No, flood basalts are not explosive eruptions, quite to the opposite. Done
The taxonomic structure then switched to sauropsids. – Already much earlier. Plateosaurus was the first really large herbivorous dinosaur, and much larger than any earlier megaherbivores; it is from the Norian.Not done I'm following what the source says.
Then we need another source, there is a large literature on dinosaurs.
This could be of interest for a late, very large synapsid: [1]
Megaherbivores first evolved in the early Permian (300 mya). The earliest megaherbivores were synapsids that went extinct 200 mya – 1) I can't find the "early Permian" claim in the source. 2) I also would state which synapsids were megaherbivores in the early Permian; at the moment this is quite unspecific.Not done Source doesn't specify
It does not make sense to me to have sections about the Permian and Cretaceous but not about Triassic and Jurassic. Done
The section structure doesn't work at the moment, not least because we have "Triassic" in (or not properly in) two separate sections. Please could we have a separate "Triassic" section, so we will have "Permian", then "Triassic", then "Cretaceous". Each one needs an account of taxonomic diversity of MH, at least a brief account of the ecological niches, and if relevant a statement about what ended the period and made the dinosaurs involved go extinct (if they did).
Two mechanisms are thought to have played major roles: an extraterrestrial impact event in the Yucatán Peninsula and flood basalt volcanism in India. However, the specific mechanisms of the extinction event and the extent of its effects on dinosaurs are still areas of ongoing research. – Not really. It is pretty much agreed on that the impact was the major cause. --Jens Lallensack (talk) 23:53, 8 January 2024 (UTC) Not done Again, sticking to what source says[reply]
No, this is simply factually wrong. The asteroid impact was the primary cause. This is one of the most salient events in the dinosaur MH era, so it is one of "the main points" required by the GA criteria. It is easily cited.
I think Jens is pretty much correct here. The effect is to pose a choice: either the article describes all periods in equal detail, with accurate coverage of the dinosaurs and geological events (per the above, the existing coverage is both skimpy and wrong in multiple ways), or we change the scope to Mammalian megaherbivores (to match, say, Owen-Smith 1989), in which case we a) remove the non-mammalian coverage, and b) AFTER THE REVIEW IS CLOSED, rename the article. (We cannot rename during the GAN as this causes the bot to fail to find the article, resulting in immediate failure.) I recommend the second option, as frankly the article is nowhere near passing as a full reptiles+mammals=megaherbivores work and I don't see sources that offer full-width coverage on that either (so we risk synthesis). Chiswick Chap (talk) 09:35, 9 January 2024 (UTC)Not done Explained below[reply]
Mammals are the main subject of almost all sources concerning megaherbivores. Wikipedia articles—like the one on crocodilias—talk mainly about living, not extinct, species. I believe it's crucial that the article concentrates on living species rather than extinct ones because doing so would violate the neutrality guideline if we gave undue weight to any one aspect. I believe I covered the topic of extinction sufficiently. I don't see any need to rename the article because I'm just following what the sources emphasize, not what I think should be included. 20 upper (talk) 11:47, 9 January 2024 (UTC)[reply]
If we were to agree on that, then we should remove the sections before Pleistocene as lacking suitable coverage. Chiswick Chap (talk) 11:51, 9 January 2024 (UTC)Not done Explained below[reply]
OK, in that case you need both to fill out the geological periods (diversity of MHs in each period, tree with images, adaptations, end events) and to rewrite the r/K and other 'Adaptation' material to cover the different evolutionary arguments for the MH dinosaurs and the MH mammals. This will be a major restructuring and will double the length of the article.Chiswick Chap (talk) 12:41, 9 January 2024 (UTC)Not done Explained below[reply]
Renaming was the second alternative; you have chosen the first one, "describe all periods in equal detail", but have not completed it. This is a pass/fail issue. Chiswick Chap (talk) 11:33, 10 January 2024 (UTC)[reply]
Evolution of megaherbivores in a nutshell: The earliest megaherbivores, synapsids, emerged 300 mya, then went extinct 200 mya in the Triassic. Sauropodomorphs took their place and occupied it from the Triassic to the Cretaceous. Then dinosaurs went extinct in the late Cretaceous. Mammals then evolved into megaherbivores in the Paleogene. There were no major extinctions until the Pleistocene, which only left nine species. I believe I've mentioned all that; if not, please be very specific as to what information is missing. 20 upper (talk) 16:21, 10 January 2024 (UTC)[reply]
The concern about synthesis has not gone away: you've indicated sources specific to dinosaurs (and to specific periods, at that). So far I've seen no single source that states in terms that MHs include both dinosaurs and mammals, i.e. that the usage of the same word is not an accidental homonym with different meanings in the two cases. It would be wise to locate such a source and provide a definition from it near the top of the article, so we have a sound basis for expansion. Chiswick Chap (talk) 12:48, 9 January 2024 (UTC)[reply]
But you are mostly citing articles that are specifically concerned with mammals, so of course they are concentrating on mammals. There are plenty of paleontology articles that talk about megaherbivores from another angle (which are not cited). A GA should be "broad in coverage", that means it should cover all relevant aspects, and fossil megaherbivores are certainly one of them. This does not mean that they need to be discussed in undue detail, but a statement like "Megaherbivores are K-selected species" is simply incorrect. It needs to have at least a sentence that this does not necessarily apply to non-mammalian species. This review [5] is a good one contrasting modern megaherbivores with sauropods, at least. Jens Lallensack (talk) 12:52, 9 January 2024 (UTC)[reply]
As you were concerned with WP:UNDUE: That page states that Neutrality requires that mainspace articles and pages fairly represent all significant viewpoints that have been published by reliable sources, in proportion to the prominence of each viewpoint in those sources. I think this means that you may put greater emphasis on mammals, but still should provide the fossil perspective in all sections where it is relevant. --Jens Lallensack (talk) 13:13, 9 January 2024 (UTC) Done[reply]
The paper Onstein Kissling 2022 talks about megaherbivore dinosaurs and mammals, and the gap in time between them. This might be useful for definitions. Chiswick Chap (talk) 13:45, 9 January 2024 (UTC) I already explained this in the article.[reply]
No, I do not see a "Definitions" section with citations that cover both dinosaurs and mammals. Chiswick Chap (talk) 11:33, 10 January 2024 (UTC)[reply]
What? The definition basically says it all Megaherbivores are large terrestrial herbivores that can exceed 1,000 kg (2,200 lb) in weight. I don't know what you want me to do here. 20 upper (talk) 16:16, 10 January 2024 (UTC)[reply]
Oh I see, it's in the lead. I'm looking at the body, as it needs to provide cited text for the lead to summarize: I presume that after all the changes that we will be rewriting the lead; while we're about it, all the refs will be moved out of the lead as no "new" material should be introduced up there, it's only a summary. The statement will need to be cited to something that covers both dinosaurs and mammals; Onstein Kissling 2022 should be suitable for that, and if possible a bit more should be said in definition, not least that a lot of sources write as if mammals were all that mattered. Chiswick Chap (talk) 16:26, 10 January 2024 (UTC)[reply]
I'm busy this evening. I'll do a third reading tomorrow, but at a quick glance the Permian needs filling out, as does the Triassic. Chiswick Chap (talk) 17:59, 10 January 2024 (UTC)[reply]
@Jens Lallensack and Chiswick Chap: The papers don't specify which synapsids or dinosaurs were megaherbivores. Furthermore, it was not stated in the papers whether previous megaherbivores were r or k selected, so this information is not necessary to add. I was citing sources with information for the various sections rather than just those with a mammal focus. This article focuses on the ecology, evolution, and behavior of living megaherbivores. Something ceases to exist when it goes extinct. Information on fossil megaherbivores only relevant in the sections on evolution and perhaps ecology, but since their ecology is essentially the same,... I will, however, extend the article to 35,000 byes. 20 upper (talk) 14:57, 9 January 2024 (UTC)[reply]
I fear I have to disagree with basically everything you said. But I am not the reviewer and should withdraw from this discussion now. If you need more clarification or information regarding the fossils, I am always happy to help. Jens Lallensack (talk) 15:03, 9 January 2024 (UTC)[reply]
That seems like a little too many phylogenetic trees, don't you think? 20 upper (talk) 19:21, 9 January 2024 (UTC)[reply]
That's one tree; or from a global perspective, we have one tree for each major period (we have one for Pleistocene, one for Recent, and I'm proposing one for Cretaceous. What's not to like. A tree is just one format, but it has the advantages (compared, say, to a list or table) of being compact, graphical, informative about relationships, and easy to illustrate. Chiswick Chap (talk) 19:35, 9 January 2024 (UTC)[reply]
Sure, buddy. I wasn't available today, but tomorrow is my day off. Hopefully, we can finish this up. 20 upper (talk) 20:33, 9 January 2024 (UTC)[reply]
I've just made my 500th edit to the page; could you please make the phylogenetic tree now? I believe I've addressed every one of your recommendations; perhaps it's time to move on to other areas of the review. 20 upper (talk) 10:02, 10 January 2024 (UTC)[reply]
Could you please mark each of my (and Jens's) items with what you feel is their status so I can see and mark progress here on this page. Chiswick Chap (talk) 10:22, 10 January 2024 (UTC)[reply]
Thanks for the tree; I've annotated every item. 20 upper (talk) 11:12, 10 January 2024 (UTC)[reply]
Note my replies on some of the items, which involve pass/fail issues. Chiswick Chap (talk) 11:44, 10 January 2024 (UTC)[reply]
For clarity this time around, could you briefly reply in text below my items (like this: ** Your text) rather than using the "Done" template; I'll strike each item when I'm satisfied it is in fact done. Thanks.
Greek and Latin: uncited. The ref should cover the whole name.
Done
Definition: still only in lead. Article needs a "Definition" section which a) makes the weight statement, b) cites it for both fossil and recent megaherbivores, and c) says something about the need for caution on applying statements about "all megaherbivores" to fossil environments.
Mostly done, but I couldn't find any source that could support point c
It's fixed by saying "recent" or "extant", so the "ALL" has effectively been dropped. Chiswick Chap (talk) 10:38, 12 January 2024 (UTC)[reply]
in the form of synapsids. This polyphyletic group of megafauna includes elephants, -- jumps from Permian to Recent. Lead needs to add mentions of Triassic, Cretaceous, Paleogene, Pleistocene, and the word "Recent" before the elephant discussion.
Done
"polyphyletic" appears only in lead.
Fixed
All megaherbivores are -- no, all extant ones, unless you have a citation to the contrary (in which case, please state clearly "All fossil and extant MH are ...." and make sure the claim is reflected in the main text, with a citation that includes fossils). This "ALL MH ARE" point needs to be fixed throughout the article. I'll refer to this item a few times below, so please, go through the whole text and make sure that every instance is unambiguously stated to be "Recent" or "Fossil and Recent".
"In terms of ecology, extant megaherbivores deviate from smaller megafauna." - This is not definitional, nor does it assist readers, so let's remove it please.
Done
Ref [1] Collins Dictionary states in terms "Tropical seagrass meadows support a diversity of grazers spanning the meso-, macro-, and megaherbivore scales." Definition section needs to state that MH include large marine herbivores, citing this source, which is named <ref name="Collins Dictionary"/>.
Whole section is "ALL MH ARE" again, but the text and sources are all "Recent". The choice is to mark the whole section boldly as Recent, e.g. rename it "Ecology of Recent megaherbivory", or to add a subsection for "Fossil" and head the current text "Recent" or "Extant", so we have
1. Ecology
1.1 Fossil
1.2 Recent
Done, implemented suggestions
Same "ALL MH ARE" goes for "Interspecific interactions". The easiest solution would be to make it a subsection of 1.2 Recent, so it becomes 1.2.1 Interspecific interactions. Actually it's not great having a section of unnumbered text before item 1, so I suggest we create 1.2.1 Grazers and browsers, 1.2.2 Interspecific interactions (or something like that).
Done
which alters the movement of resources: which means what, exactly?
This is what the source said "impacting on the recycling and spread of nutrients"
No good explaining here, the text is unclear for the general reader. Please edit.
they altered trophic cascades: how? in what way?
According to source "Megaherbivores should respond less to the landscape of fear, thereby counteracting the effects of fear-triggered trophic cascades" (le Roux et al., 2018, Current Biology 28, 2493-2499 August 6, 2018)
No good explaining here, the text is unclear for the general reader. Please edit.
Permian: why not illustrate Dinodontosaurus, there is a good reconstruction in that article.
Added image
I've added a tree; as well as the Synapsids, it shows the Pareiasaurs, which need a mention and ref in the text.
Done
Triassic: you begin with the extinction at the end of the period, so what happened all through the Triassic, then?
Mentioned in Permian, synapsids went extinct right around the end of the Triassic
You now write: In the Triassic–Jurassic extinction event, synapsids went extinct. No. We humans are synapsids, and we are still living. Not even synapsid megaherbivores went extinct during that event; they went extinct earlier (the Triassic-Jurassic extinction event is not even mentioned in the source you provide?). --Jens Lallensack (talk) 17:29, 11 January 2024 (UTC)[reply]
I do not believe you. 20 upper (talk) 17:41, 11 January 2024 (UTC)[reply]
No reason to get angry. You listed the article at GAN, therefore you asked for constructive review comments. Now you get what you asked for, and we hope they will help you to improve the article. We are all volunteers, and such reviews should not be taken for granted. We have other things to do too, as you can imagine (and nobody is obliged to continue any review if it gets unpleasant). You could save much reviewer time by taking the concerns serious rather than dismissing them. Thanks --Jens Lallensack (talk) 18:19, 11 January 2024 (UTC)[reply]
We need a ref for the T-J extinction event.
Done
It isn't clear that any of the four current citations, [5][13] for the dicynodont claim, or [14][4] for the flood basalts causing extinctions, are actually suitable for supporting the claim that flood basalts or something else caused a massive T-J extinction event (which [13], half a history-of-science paper, thinks is based on minimal evidence, and which [14] explicitly says may never have happened). Either we need a solid, recent, geologically- and paleontologically-well informed source that actually states in terms that there in fact was a T-J extinction event, despite all the worries about it, or we should remove the claim as too wobbly to be worth mentioning, or (perhaps) we should mention it with *a lot of caution*, i.e. "Some scientists have proposed that there might have been a T-J extinction event,[123] but others ... [13][14]", that sort of thing. And even if it existed, we definitely don't know its cause. At the moment the whole thing reads as non-neutral.
Explained
Triassic: The taxonomic structure then switched to sauropodomorphs. So that's after the T-J extinction, i.e. it's in the Jurassic? Looks as though we're missing a "Jurassic" section, and the claim should go in there. Suggest you describe and illustrate Triassic taxa.
Added Jurassic section
New taxa may have caused competitive exclusion, or they may have adopted the ecological niche of past groups. Please be clear for the reader here. The first means that the new taxa outcompeted and removed the old ones; the second means, the old ones just vanished (unexplained) so the new ones took their spots with no effort.
Done
Jurassic: What taxa here? – certainly not just Sauropods.
Done
Cretaceous: Again, not just Sauropods. The single-sentence does not do justice to the complex MH ecology of the period; we know that the nicely-illustrated diversity of dinosaurs had different ecologies (feeding methods, for a start). There is a wealth of sources; we can't do everything but "the main points" requires some sort of discussion here. [21] by the way gives a lot of detail on dentition and hence on feeding methods, a useful source.
Done
Much improved. There is definitely scope for far more discussion here but the basic concept is now conveyed.
Paleogene: Please mention some of the MH that lived in the Eocene and Oligocene, such as Paraceratheriidae. Again, there's a good illustration in that article so do use it.
Done
Paleogene: The marine Sirenia (including the Manatees and Dugongs) became megaherbivores in the Eocene (i.e. within the Paleogene), e.g. the genus Eosiren lived then. This needs to be added and cited.
I was able to locate citations that backed up the idea that Sirenia are megaherbivores, but I was unable to locate any that stated Eosiren was a megaherbivore.
There are many Eocene genera. this discusses Eocene and modern Sirenians as megaherbivores.
Done
Mammals were as large as megaherbivores - what does this mean? If they were herbivorous, they *were* MH; if carnivorous, what is your point?
Fixed
Pleistocene: There were around 50 different species by the Late Pleistocene: [tree] Today, nine of the 50 species persist. This says exactly nothing about the ecology of MH in the Pleistocene, but jumps straight to their decline. How did they live? It is evident that they had a wide range of ecological niches, diets, and habitats, which need to be discussed.
"Adaptations and size, Size, K-selection, Reproduction, Lifespan and mortality" are all "ALL MH ARE" material, and must be clearly marked as "Recent" unless you find and cite Fossil sources to the contrary.
Done
They are also all about Adaptations, so I suggest we have a single chapter with subsections. The first section is so short it should be merged.
Done
face no threats from predators – this is untrue. The threats are greatest to eggs and young, decreasing with size. Please say so, and cite it.
Done
No, the claim is still there at the top of "Browsers and grazers". Bigger animals are not invulnerable, just less likely to be attacked, so the "with the exception of calves" is still untrue. Please watch the the BBC Planet Earth clip, a reliable source, showing a pride of lions taking down a full-sized elephant. Watch from 5:50 if you want to cut to the chase. You may use {{cite media}} if you want to cite this source, but written sources are equally available.
Ooh, I know that clip, I assume it's from Ultimate Enemies: Elephants and lions (2003). I haven't viewed that documentary in a very long time. That looks like a sub-adult elephant based only on size. I've been close to those creatures, and they're gigantic. Excellent sighting; it's certainly not common. I've made the proposed adjustment based on the footage.
There are a lot of "N,000" figures. Why not just say "N tonnes" (abbreviated to "t") throughout (and forget the conversions, long tons are almost the same as metric tons).
There is no apparent function to the two images in "Reproduction" with the current captions. Please explain in the captions what encyclopedic point is being made (e.g. rhino calves are vulnerable to predators, and stay close to their mothers for safety for N months... Giraffe calves don't stay with their mothers, they sit down and hide for most of the day, and their mothers briefly visit to feed them). Something like that. Any such claims need to be cited.
Done
All the images are from Commons, where they seem to be appropriately licensed.
The article is much improved. The main remaining issue is the way that claims about Recent animals and their ecology are made to appear to apply to paleontological times, without evidence. Chiswick Chap (talk) 13:12, 11 January 2024 (UTC)[reply]
Now that things are regrouped, the article is far clearer, but it is now also apparent that 2. Ecology (recent) 3. Evolution (mostly ancient) 4. Adaptations (recent) is a bit haphazard. Could you please move the Ecology chapter after Evolution. Thanks.
The article states that Megaherbivores are large terrestrial herbivores. However, the cited source does not seem to explicitly state that megaherbivores are necessarily terrestrial. In fact, the hippopotamus is semi-aquatic, and sirenians are often referred to as megaherbivores too (numerous papers turn up if you enter megaherbivore and sirenia in Google Scholar). So it seems that the statement "There are nine extant species of megaherbivores" is not as uncontroversial as presented in our article.
What about the term "megafauna"? How is this term related to "megaherbivore"? I think this is something that could be discussed under "definition". --Jens Lallensack (talk) 18:44, 11 January 2024 (UTC)[reply]
This has been added to Definition. Chiswick Chap (talk) 09:31, 12 January 2024 (UTC)[reply]
The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
