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What the hell is up with the JW allosaurus covering the Adasaurus image?

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When I click on the image, it redirects to the normal Adasaurus image file. I have replaced the Adasaurus image with a skull diagram Bubblesorg (talk) 01:40, 21 June 2025 (UTC)[reply]

nemegts age

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basically bubbles Borg keeps changing the age of the lower to the campanian, I revert it because I have many issues with it.


  1. the stratigraphy is as follows djadochta is oldest, barun goyot is in the middle, and the nemegt is the youngest. the djadochtas top its youngest part has been radiometrically dated to be 71 million years old. the bG and the nemegt is younger than that age and are both preceded by in succcessive rocks to djadochta. it makes no sense for the Nemegt to be in the campanian in that regard.
  2. the 2023 study dated the middle Nemegt to be 66.7 mya plus or minus 2.5 mya. even if you add that extra, the middle Nemegt has been well constrained into the maastrichtian, the lower would have to span millions of years, which I'm not buying.
  3. he cites a 2021 claiming both the upper most bg and the lower most Nemegt are the same, that study is not universally accepted to my knowledge. even if they are, the bG itself is constrained well within the maastrichtian so the nemegt still wouldn't touch the campanian if the study is true.
  4. there's a mountain of evidence constraining the Nemegt from bottom to the top within the maastrichtian. the presence of the maastrichtian genus saurolophus(found from the lower to upper Nemegt btw), the upb dating which is the most precise dating methods done yet for nemegt and the radiometric date of djadochta and the age of barun goyot.


all this in mind stating the Nemegt as being anywhere in the campanian seems like a bridge to far. it upsets the chronological order of the pages of barun goyot and djadoctha formations and as I've pointed out seems very shaky with all the evidence I layed out.


not saying it cant be Campanian in age but as it stands it seems like a bridge to far to put it in.

Themanguything (talk) 22:09, 22 September 2025 (UTC)[reply]

To clarify, I put it as 72.1 MYA at the earliest, which corresponds to the latest Campanian. There is little recent evidence to suggest that the formations are strictly sequential; in fact, the most recent findings indicate they were, to some extent, concurrent. The 2023 paper only specifies the middle and upper portions of the formation and even states that a Campanian deposition is possible for the Nemegt. Your statement of “I’m not buying it” is simply a personal opinion and not a scientific argument. Regarding the ±2.5 MYA number—where did you get that? The Djadokhta Formation itself dates from approximately 75 to 71 MYA, which is a span of 4 million years. You also mentioned that the 2021 study is “not universally accepted.” Can you provide any dissenting views or papers that explicitly contradict it? I’ve looked at all the papers citing the 2021 study, and none of them present conflicting evidence. Lastly, your final statement is uncited, and much of what you’ve presented here appears to be based on personal interpretation rather than objective data. As it stands, there is no source you can cite about the lower Nemegt specifically.--Bubblesorg (talk) 22:32, 22 September 2025 (UTC)[reply]
not providing anything for the lower nemegt specifically is no issue. the djadochta and barun goyot overly it conformably and the information we have on their ages isnt supportive of a 72 million year age, they are older than the lower Nemegt and conformably preceded it so any age information gotten from them is applicable to the nemegt.
and the paper from 2023 gives a 2.5 million year give or take age, its the plus or minus sign the plus sign with the line underneath it.
and as I've said the top of djadochta is radiometrically dated to be 71 million years old and because of the conformity with bg and Nemegt it would make every part of Nemegt and barun goyot younger than the djadochtas top. and so the 72 million year age you put is completely inconsistent with what I said previously, the lower Nemegt would have to be older than barun goyot and the top of the djadochta for that age to make any sense at all and stratigraphically it makes 0 sense. Themanguything (talk) 23:24, 22 September 2025 (UTC)[reply]
Okay, the 2.5 MYA is simply the margin of error for the 66 MYA date, which is very common in geology papers and even in chemistry research. A margin of error is included whenever scientists are measuring things to indicate possible variation in the data. It does not mean the formation itself represents a continuous span of 2.5 million years. As I mentioned, it’s also very likely that these formations are not perfectly sequential but instead overlap significantly in time. You claim this idea of overlap is contested — by who, exactly? Seriously, find me a post 2021 paper that actually disputes this concept. None do. --Bubblesorg (talk) 00:01, 23 September 2025 (UTC)[reply]
even if the lower Nemegt and uppermost bg are overlapping a Campanian age for Nemegt is not supported because bg itself generally considered maastrichtian in age, only the base of bg comes close and even then the lower Nemegt only touches the uppermost part not the bg's base. this is further backed up by the radiometrics of the djadochta (which as of now baruungoyot is still sequential to). Themanguything (talk) 00:13, 23 September 2025 (UTC)[reply]
ill concede to the idea of lower Nemegt and baruungoyot interfingering but still the radiometrics of djadochta and the accepted age of barun goyot makethe 72 million year old age you put in for Nemegt very shaky. lets wait until abritrators can come here. there's no point in spamming this with broken record back and forth Themanguything (talk) 00:20, 23 September 2025 (UTC)[reply]
and please wait until this dispute is settled by arbitrators before saying "every dinosaur from the lower Nemegt is campanian in age" plus therizinosaurus and deinocheirus are known from the middle part as well,which has the upb dating to consider. Themanguything (talk) 00:41, 23 September 2025 (UTC)[reply]
As far as I can tell this dispute concerns primarily the claim:
  • The lower part of the formation is probably upper Campanian.
sourced to
  • Fanti, F.; Currie, P. J.; Badamgarav, D.; Lalueza-Fox, C. (2012). "New specimens of Nemegtomaia from the Baruungoyot and Nemegt Formations (Late Cretaceous) of Mongolia". PLOS ONE. 7 (2): e31330. Bibcode:2012PLoSO...731330F. doi:10.1371/journal.pone.0031330. PMC 3275628. PMID 22347465.{{cite journal}}: CS1 maint: article number as page number (link)
together with a change to the age parameter of the {{infobox rockunit}} which is unsourced.
A second source was added in support of additional content:
One of the edit summaries claims this source is unreliable without evidence given.
I think the specific content in these articles that support ages for the formation should be quoted here in the Talk page. I did not find anything specific in these sources.
Unfortunately the discussion above refers to dates of sources which is not helpful and includes a lot of addition discussion other than sources.
The source for most of the Stratigraphy content is Eberth-2018
who says "The age of the Nemegt Formation is widely regarded as Maastrichtian (e.g., Khand et al., 2000) but more precise ages for its boundaries and subdivisions are still lacking." and "On the basin scale, the age and nature of the boundary between the Baruungoyot Formation and overlying Nemegt Formation is poorly understood"
  1. I think the Stratigraphy content should be changed to clarify the considerable uncertainty.
  2. I don't think the Shuvalov ref should be used here: Eberth-2018 reviews the Shuvalov results.
  3. I think content based on the Jerzykiewicz-2021 source should not be interleaved with the Eberth-2018 content. It's an interesting new take and we should approach it that way in a separate paragraph. Something like "While a temporal succession of the Djadokhta, Baruungoyot, and Nemegt formations has been hypothesized, they may represent different parts of a single interconnected ecosystem,..."
  4. I think we need a better source for the claim about "probably upper Campanian".
HTH Johnjbarton (talk) 01:28, 23 September 2025 (UTC)[reply]
my contention is we have good radiometric dates that put the top of djadochta at 71 million years old. only the lower Nemegt and upper BG have any evidence of interfingering and being contemperanous. the idea of barungoyot being sequential to djadochta however is still the consensus. and under that the barungoyot would be younger than 71 million years old, and again its older than Nemegt, so it makes the entire idea of the Nemegt being 72 million years old just questionable. Themanguything (talk) 01:49, 23 September 2025 (UTC)[reply]
However, we *lack* dating for the Djadochta and Baruungoyot so there is theoretically nothing preventing the lower Nemegt from being Campanian even if the middle Nemegt is Maastrichtian. The 75-71MA age for the Djadochta is based on magnetostratigraphy correlations and not radiometric dating, which means it is still subject to correlation interpretations. At this point, there is nothing saying the Nemegt is Campanian, so that should be removed from all but historical comments, but there is also nothing giving age ranges for the entire formation, so that similarly should be removed. The summary by Johnjbarton is correct and should be followed. IJReid {{T - C - D - R}} 02:50, 23 September 2025 (UTC)[reply]
no the djadochta has been radiometrically dated http://digitallibrary.amnh.org/bitstream/handle/2246/5667/N3498.pdf?sequence=1&isAllowed=y
and once again its age at the top is 71 million years ago Themanguything (talk) 03:12, 23 September 2025 (UTC)[reply]
sorry didn't finish reading the sentence. well I mean as it stands what we do have until proven otherwise suggests going from the djadochtas top to younger rocks is 71 million years or younger. Themanguything (talk) 03:17, 23 September 2025 (UTC)[reply]
as of now because of the perpetual uncertainty regarding Nemegts age it needs to be left at 70-66 mya for now because that is the best age we can justify as being, beit mag-strat,upb dating or the biostratigraphy of saurolophus.
the 2013 paper he lists isn't enough to shake it up because it relies on the same uncertain guess work and isnt nearly enough to settle the age debate. Themanguything (talk) 03:20, 23 September 2025 (UTC)[reply]
remember how you said they "may" be contemporanous rocks. that's what I meant by it not being universally accepted. its an out there idea as of now. Themanguything (talk) 01:59, 23 September 2025 (UTC)[reply]

Hi people, hope everthing's fine. I must admit that this is an exciting discussion because the age of the Nemegt Formation has been a hot topic in literature, and not only Nemegt, but also the Djadokhta and Baruungoyot formations. I've highlighted the most relevant papers and authors so we can have a better understanding for the age debate, so keep in mind that there are others that I'm missing:

  • Eberth et al. 2009 made special observations on the Baruungoyot-Nemegt stratigraphic transition, and interestingly enough found a 23 m thick section where these formations intersect: during a certain time both Baruungoyot and Nemegt paleoenvironments and vertebrate faunas co-existed, insane right?
  • Eberth 2018 separates the Nemegt Formation into three stratigraphic intervals: a lower, middle, and upper members, and these represent changing depositional environments. I recommend checking out Figure 2, 6, 9, 13, and 18, very comprehensive work. As a whole, the result for this stratigraphic analysis suggest that the paleoclimatic conditions during the deposition of the Nemegt Formation changed varied from humid/well-watered to seasonally wet-dry to arid, and then back to seasonally wet-dry. No age involved here, but the Baruungoyot-Nemegt stratigraphic transition is again mentioned.
  • Jerzykiewicz et al. 2021 suggested that the Nemegt, Baruungoyot, and Djadokhta formations are separated by space, not strictly time, and I think this paper is of major relevance because it directly discussed an idea previously noted by Eberth and colleagues. They argue that the Nemegt-Baruungoyot-Djadokhta strata is preserved laterally across the Nemegt Basin, rather than in superposition as one would expect from most succesive units. They also argue that the term formation is difficult to apply when working across these units because of the geological irregularities, such as grabens, that occur in the Gobi Desert, hence coining the term lithobiotope in order to include paleofuna + lithofacies. Also, they indicated that a great deal of the same dinosaur taxa (or very similar) is frequently encountered in these units, further reinforcing this conception of "formations existing at the same time".
  • According to Tanabe et al. 2023, the deposition of the middle Nemegt Formation occurred BEFORE 66.7 ± 2.5 Ma, which is safely consistent with a Maastrichtian age for the formation. They also conclude that the upper and middle sections of the formation are likely to have occurred during the Maastrichtian. Still, their results can't argue against a late Campanian depositional age.

I perceive that a lot of the comments surrounding the 70 Ma vs 72 Ma (or other ages) come from the Formation/Age sections in many papers describing particular dinosaur specimens, some of which also cite other authors. To exemplify:

  • Weishampel et al. 2008: "If the Nemegt Formation constitutes a contiguous sedimentary body within the Nemegt Basin, this would date Bugin-tsav within the 72.0–70.8 Ma interval (Ogg et al., 2004; e.g., late Campanian)."
  • Bell et al. 2017: "The age of the Nemegt Formation is widely regarded as Maastrichtian, but more precise ages for its boundaries and subdivisions are still lacking."
  • Stettner et al. 2018: "The Nemegt Formation is the youngest of the Cretaceous formations present in the Gobi Desert (Upper Campanian-Lower Maastrichtian)."

If you actually took the time and read these works, you will notice that the authors that have comprehensively studied the Nemegt Formation (and adjacent units) do not provide specific, mandatory ages because the geology of the Gobi Desert and Nemegt Basin is quite complex. The absence of certain elements such as marine invertebrates, datable volcanism-derived sediments, plants, and geological irregularities, prevent the Nemegt Formation from having absolute datings. The way I see it, it is pointless to argue over specific numbers when there isn't a single paper discussing radiometric dating. In that view, what could be done here (and may be the safest choice for now) is to assign the age to Late Campanian-Maastrichtian which IS the most widely regarded interval for the formation across experienced authors. As a last comment, we should note that this whole age debate is very ambiguous considering the growing evidence for these units being an entire connected system that evolved through time. PaleoNeolitic (talk) 04:49, 23 September 2025 (UTC)[reply]

as it stands I think the ages of the formations need to be left as be. nothing is strong enough to say "likely latest Campanian" or anything like that. they need to left be until more precise analyses settle this debacle. sorry bubble borg for constantly reverting, we both learned something here. Themanguything (talk) 06:15, 23 September 2025 (UTC)[reply]
Tanabe et al. (2023) seems to be a good source for our purpose, as the paper is recent and specifically deals with the age of the Nemegt. They actually say that deposition began in the "late Campanian or Maastrichtian", and make clear that we currently can't tell. Maybe putting "late Campanian (?) to Maastrichtian", with a question mark to indicate this uncertainty, and sourcing that to Tanabe et al. (2023) would be prudent? --Jens Lallensack (talk) 06:33, 23 September 2025 (UTC)[reply]
Yeah that works, I like the idea of a possible Late Campanian to Maastrichtian date. Also, the Djadochta was not radiometrically dated, it was magnetostratigraphically dated--Bubblesorg (talk) 13:50, 23 September 2025 (UTC)[reply]
I would agree on that, sounds consistent with authors and research. Still, I'm not sure if the right approach is to provide specific numbers. PaleoNeolitic (talk) 14:29, 23 September 2025 (UTC)[reply]
Let's be clear on exactly what the Tanabe et al. (2023) says:
  • Although no radiometric dating has yet been performed directly from the Nemegt Formation, a comparison of the faunal composition between Mongolia and North America suggests that the deposition of the Nemegt Formation occurred from late Campanian to Maastrichtian.
We should use the same qualifications (based on faunal composition, "suggests") on any claims we make about age. Johnjbarton (talk) 16:07, 23 September 2025 (UTC)[reply]
So what would you suggest for the infobox, where we have to be concise? --Jens Lallensack (talk) 16:55, 23 September 2025 (UTC)[reply]
I added a sentence that I think matches the discussions here. Johnjbarton (talk) 16:32, 23 September 2025 (UTC)[reply]
It seems we agree that Jerzykiewicz et al. 2021 should be included. I will add a paragraph based on a modification Bubblesong's addition, but not in the same paragraph as the Eberth analysis. Johnjbarton (talk) 16:20, 23 September 2025 (UTC)[reply]
I thought this discussion over? Nevermind. The infobox can include a question mark. The date range should be listed as 72.1–66 MYA. This is because 72.1 MYA marks the transition from the Campanian to the Maastrichtian stage. Therefore, referring to any point at 72.1 MYA as either Campanian or Maastrichtian is accurate. Also, the listing of the Baruungoyot Formation as "Early Maastrichtian" is unsupported. The dates provided in that article are likely inaccurate or even fabricated. The most recent studies I found instead suggest a Campanian age. https://www.nature.com/articles/s41598-021-83568-4 --Bubblesorg (talk) 17:29, 23 September 2025 (UTC)[reply]
The above discussion makes it clear that we should NOT provide specific numerical ages in the date range because this is unsourced and cannot be validated. An age range of 72.1-66 is simply mapping the current boundaries of the Maastrichtian, which is undesirable because it gives a false sense of confidence, and also because the age of the Maastrichtian is constantly changing (note how Weishampel et al. 2008 describe 72.0-70.8 as Campanian because 70.8 was the accepted boundary at the time). IJReid {{T - C - D - R}} 17:46, 23 September 2025 (UTC)[reply]
Sorry, my mistake—I thought someone said we should include a date. In that case, we should probably leave it without a specific date and just write something like “Late Campanian (?) – Maastrichtian.” Anyway, what about the Baruungoyot dates? The ones listed don’t seem to be accurate. --Bubblesorg (talk) 17:53, 23 September 2025 (UTC)[reply]
I'm not sure about removing the dates from the infobox entirely. Yes, they map the boundaries of the stages, but that's how we do it everywhere (e.g., dinosaur). It's only an accessibility feature; an explanation to the lay person what we mean with "Maastrichtian" (easy-to-verify information that is just added to make articles understandable does not need an extra source). And if we use the templates, the frequent boundary changes are not an issue too as we only need to update the template. To make a concrete suggestion, what about "Maastrichtian (possibly also late Campanian), ca. 72–66 Ma" for the infobox? This implies that the 72–66 Ma does not include the possible Campanian. --Jens Lallensack (talk) 19:11, 23 September 2025 (UTC)[reply]
In the Dinosaur article the exact ages are given by the radiometric dating of the Santa Maria fauna, and not the boundary of a geological epoch, which makes it different here where we would be defining the date from the epoch rather than the epoch from the date. A precedent for this exists in many articles such as Therizinosauria where "Cretaceous" is given, rather than 145-66mya (the boundaries of the Cretaceous). I've made an edit to display how it appears to be agreed by this discussion, to see what others think. IJReid {{T - C - D - R}} 22:12, 23 September 2025 (UTC)[reply]
what do y'all think the age of the the nemegt might Be? Dinodev123 (talk) 07:04, 25 September 2025 (UTC)[reply]
I mean like still an ongoing debate but do you think it's early or middle or late Maastrichtian. What I actually did is I researched the climate trends going on in the songliao basin of China and compared that to the climate transitions recorded from the barun goyot to nemegt formations. Since Mongolia is part of East Asia and like China needs the East Asian monsoon for it's rainfall and was the same way in the Cretaceous I figured that depending on how I matched up the climate correlations it could potentially supplement the upb dating. https://www.reddit.com/r/Paleontology/comments/1ndp9x9/nemegt_formations_age_my_argument_for_a_late/ defer to this Reddit post. Long story short the wetting trend of the lower and middle nemegt transitioning into the relatively drier conditions of the upper nemegt was more in line with the wetting trend of the middle Maastrichtian and then the subsequent drying trend that was happening from 69 to 66 million years ago, lining up with the upb dating pretty well. Dinodev123 (talk) 07:10, 25 September 2025 (UTC)[reply]
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