Patagopelta new remains + Nopcsaspondylus as rebbachisaurid + dinosaur tracksites from Jurassic of Morocco

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

New papers:

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Federico L. Agnolín, Sebastián Rozadilla, Jordi García Marsà, Rodrigo Álvarez Nogueira, Santiago Miner, Gerardo Álvarez-Herrera, Fernando E. Novas & Diego Pol (2026)
New remains of the armored dinosaur Patagopelta cristata Riguetti et al. 2022 (Ornithischia, Parankylosauria) from the Late Cretaceous of Patagonia, Argentina
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2025.2583504
https://www.tandfonline.com/doi/full/10.1080/08912963.2025.2583504


The fossil record of Southern Hemisphere thyreophorans has expanded significantly in recent years. Among notable discoveries is the armoured dinosaur Patagopelta cristata, from Maastrichtian beds in northeastern Patagonia. This taxon was described from disarticulated elements collected at ‘Salitral Moreno’ (Río Negro, Argentina), with a cervical half-ring designated as the holotype and additional materials from multiple individuals referred to it. However, the precise geographical provenance of these remains within the area is unknown. This contribution describes newly collected armoured dinosaur material from Salitral Moreno that provides key anatomical and phylogenetic information. The new material, comprising cranial elements, partial limbs, vertebrae, sacrum, pelvis, and osteoderms, is assigned to Patagopelta. These remains reveal a relatively plesiomorphic pelvis and an armoured tail resembling that of the parankylosaur Stegouros. Incorporation of these data into a comprehensive phylogenetic analysis places Patagopelta within Parankylosauria, closer to Antarctopelta and Kunbarrasaurus than to Stegouros. These findings support the interpretation of parankylosaurs as a distinct Southern Hemisphere radiation of thyreophorans, exhibiting greater body size, morphological, and likely ecological diversity than previously recognised.

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Lucas N. Lerzo (2026)
The lost fossil of the first discovered rebbachisaurid: reassessment of Nopcsaspondylus alarconensis (Diplodocoidea, Sauropoda)
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2025.2594006
https://www.tandfonline.com/doi/full/10.1080/08912963.2025.2594006


Rebbachisauridae is a group of diplodocoid sauropods mainly record from the Hauterivian to Turonian of Europe, Africa and South America. They were specifically abundant for the Cenomanian-Turonian times of Patagonia, Argentina. At now, at least six species have been recovered from the Huincul Formation, out of the 22 species currently known. However, the fragmentary nature of the bones and the isolated remains may generate an overestimated number of species. Nopcsaspondylus is known by a middle to posterior dorsal vertebra which is currently lost. The reassessment of Nopcsaspondylus does not find any diagnostic character which allows to recognise as a distinct species of rebbachisaurid. In addition, the erection of Nopcsaspondylus did not follow certain recommendations of the International Code of Zoological Nomenclature (ICZN), allowing to determinate that Nopcsaspondylus represents a nomen dubium.

====

Omar Ait Haddou, Abdelkbir Hminna, Abdelouahed Lagnaoui, Hendrik Klein, Mohamed Arouch, Mohamed Fergougui, Aziz Rmich & Wahiba Bel Haouz (2026)
New dinosaur tracksites from the Middle-?Late Jurassic of Msemrir (Central High Atlas, Morocco)
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2025.2596117
https://www.tandfonline.com/doi/full/10.1080/08912963.2025.2596117


In the Atlas System of Morocco, Jurassic and Cretaceous formations are well represented by continental deposits, known as red beds, famous for their abundance of vertebrate and invertebrate body and trace fossils. The Msemrir region represents one of the synclines of the Central High Atlas where these red beds outcrop. Recent research in this area has led to the discovery of new ichnological sites in the upper part of the Tilougguit Formation (Late Bajocian-Early Bathonian) and the Guettioua Formation (Bathonian–?Callovian – Late Jurassic). These ichnosites are dominated by dinosaur tracks, mainly from theropods and by tracks of a quadrupedal dinosaur, possibly a stegosaur or a sauropod, often associated with invertebrate trace fossils. Theropod tracks and trackways include morphotypes similar to the ichnogenera Changpeipus, Carmelopodus, Kayentapus, and Grallatoridae indet. These new ichnoassemblages are documented and described here in detail for the first time. Furthermore, they give insight into Middle-? Late Jurassic dinosaur communities and their environment, while opening up hopeful perspectives for further exploration and discoveries in the Msemrir region.

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[Edward Warburton]

I'd rather like to see the Patagopelta paper, if that is not asking too much.

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[Tim Williams]

Agnolín et al. (2026) has Parankylosauria comprising _Stegouros_, _Minmi_, _Kunbarrasaurus_, _Patagopelta_, _Antarctopelta_, and maybe _Yuxisaurus_ (as the most basal member, though support was not high).  I believe the family-level name Minmidae is available for the clade that includes _Minmi_, _Kunbarrasaurus_, _Patagopelta_, and _Antarctopelta_ (I have the attribution for Minmidae as Paul 2010, but I doubt it has a phylogenetic definition).  

In general, I'm not sure the name Parankylosauria (erected by Soto-Acuña et al. 2021) was the best choice for the clade that includes _Stegouros_, because it assumes a complementary Euankylosauria.  However, this ceases to be the case if _Stegouros_ falls outside a Stegosauria + Ankylosauria clade, as in Fig. 60B of Agnolín &c.  The latter supports the traditional hypothesis that stout limbs and broad feet (the reason for the name Eurypoda) are primitive for the Stegosauria + Ankylosauria clade rather than convergent between Euankylosauria and Stegosauria. 

Interestingly, the implied weight analysis in the Supplementary Online Material has _Anoplosaurus_ inside Stegosauria.  I don't recall seeing _Anoplosaurus_ come up as a stegosaur before.  Just as interestingly, the same tree has _Mongolostegus_ inside Ankylosauria.

[Mickey Mortimer]

Paul (2010) only used the term "minmids", not "Minmidae", which falls afoul of ICZN Article  11.7.1.1. that says a new family name must "be a noun in the nominative plural formed from the stem of an available generic name." The only exception is Article 11.7.2 that says if it "was published before 1900, in accordance with the above provisions of this Article but not in latinized form, it is available with its original author and date only if it has been latinized by later authors and has been generally accepted as valid by authors interested in the group concerned and as dating from that first publication in vernacular form."

I don't think the name Parankylosauria necessitates it be the sister taxon of Ankylosauria. It's like Parasuchia being convergent on crocodylians but separated by quite a few nodes. Although in the equal weights tree (as shown in Supplementary Online Material Figure S2), parankylosaurs ARE ankylosaurs, which I think makes the name less sensical.

As for the phylogenetic analysis, it's based on Raven et al.'s, which I've commented on here a couple times. It gets some weird results that to me either suggest scoring issues or thyreophoran phylogeny not being as resolved as we thought. Although I must say Agnolin et al.'s results look better in e.g. getting a 'monophyletic' Stegosauria with a normal branching order, but I do wonder how much is due to adding 24 characters and Yuxisaurus and Stegouros and how much was do to excluding 11+ taxa like Dracopelta and Paranthodon that fell out in weird positions before.

Mickey Mortimer

[Tim Williams]

Mickey Mortimer <therizino...@gmail.com> wrote:

> Paul (2010) only used the term "minmids", not "Minmidae", which falls afoul of ICZN Article  11.7.1.1.

Oh good.  Minmidae can be disregarded.  _Minmi_ is not the best genus to name a clade after.  On the other hand, _Stegouros_ is an excellent choice for any family-level clade.

> I don't think the name Parankylosauria necessitates it be the sister taxon of Ankylosauria. It's like Parasuchia being convergent on crocodylians
> but separated by quite a few nodes. Although in the equal weights tree (as shown in Supplementary Online Material Figure S2), parankylosaurs ARE
> ankylosaurs, which I think makes the name less sensical.

Both Parankylosauria and Euankylosauria were originally established to be mutually exclusive subclades within Ankylosauria.  I know this doesn't preclude Parankylosauria being outside of Ankylosauria; but if _Stegouros_ pops up in an even more basal position within Thyreophora, then we get the strange situation where Ankylosauria and Eurypoda are both inside Euankylosauria.  Of course, this would require a pretty radical shift in thyreophoran topology.  On that...

> As for the phylogenetic analysis, it's based on Raven et al.'s, which I've commented on here a couple times. It gets some weird results that to
> me either suggest scoring issues or thyreophoran phylogeny not being as resolved as we thought.

Yes, and if something really weird is going on with thyreophoran phylogeny, then it might be more sensible to have a more strictly defined clade based on _Stegouros_ (i.e., lots of external specifiers).  Such as: a new clade Stegouridae defined to include _Stegouros_ but not _Ankylosaurus_, _Nodosaurus_, _Polacanthus_, or _Stegosaurus_.

[Mickey Mortimer]

"...  if _Stegouros_ pops up in an even more basal position within Thyreophora, then we get the strange situation where Ankylosauria and Eurypoda are both inside Euankylosauria."

Fonseca et al. (2024) actually thought of that when registering the official Phylocode definition of Euankylosauria- "The largest clade within Ankylosauria and containing Ankylosaurus magniventris Brown, 1908 and Nodosaurus textilis Marsh, 1889 but not Stegouros elengassen Soto-Acuna et al., 2021." So Euankylosauria has to be in Ankylosauria to exist. As they wrote- "The name Euankylosauria has been informally defined before by Soto-Acuna et al., (2021) who defined the clade as all taxa closer to Ankylosaurus magniventris than Stegouros elengassen. Such a definition is problematic under the current understanding of ankylosaur systematics as it allows for Euankylosauria to be more inclusive than Ankylosauria if Stegouros elengassen resolves outside Eurypoda (see the position of Minmi paravertebra in Raven et al., 2023) and also allows for Euankylosauria to be less inclusive than Ankylosauridae if Stegouros elengassen resolved within Ankylosauridae (see the position of Kunbarrasaurus ieversi in Raven et al., 2023). The present definition should be a more robust solution than the previous proposal..."

Mickey Mortimer

[Sean McKelvey]

I don't have anything of note to add here, I just wanted to make it known that Stegouridae sounds better to my ears than Minmidae anyway.

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[Tim Williams]

Mickey Mortimer <therizino...@gmail.com> wrote:

> Fonseca et al. (2024) actually thought of that when registering the official Phylocode definition of Euankylosauria- "The largest clade within Ankylosauria and containing 

> Ankylosaurus magniventris Brown, 1908 and Nodosaurus textilis Marsh, 1889 but not Stegouros elengassen Soto-Acuna et al., 2021." So Euankylosauria has to be in

> Ankylosauria to exist. 

Thanks - I'd missed that.  This is prudent of Fonseca &c, to define Euankylosauria such that it must be *within* Ankylosauria.  I'm surprised they didn't do the same for Parankylosauria to (in their words) "prevent unintended applications of the clade."  That way, if _Stegouros_ is found not to be an ankylosaur, then the name Parankylosauria no longer exists.

Sean McKelvey <smc...@gmail.com> wrote:

> I don't have anything of note to add here, I just wanted to make it known that Stegouridae sounds better to my ears than Minmidae anyway.

TBH, I don't mind the name itself - as long it's spelled Minmiidae.  I guess it would be pronounced Min-my-i-dae, to reflect the pronunciation of _Minmi_ (Min-my).  It's just that _Stegouros_ is known from much better material, so therefore a better eponym than _Minmi_.

[Sean McKelvey]

Just as a reference, Minmi, as in Minmi Crossing (the namesake of the Dinosaur) is pronounced "Min-Me". So I presume that the pronunciation is the same?

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[Tim Williams]

Sean McKelvey <smc...@gmail.com> wrote:

> Just as a reference, Minmi, as in Minmi Crossing (the namesake of the Dinosaur) is pronounced "Min-Me". So I presume that the pronunciation is the same?

Interesting.  I had thought the pronunciation was "Min-my".

For example, this from Darren Naish @TetZoo (via social media):

"#2019SVP Ok, I asked Ralph Molnar about Minmi. He said that he always _used_ to say min-mee, until he visited the location 

and spoke to people there (Europeans, not indigenous).They say min-my, so it's his take this is the 'correct' pronunciation, as 

per @GondwanaGaia's talk."

[Sean McKelvey]

Interesting that locals told him it was pronounced that way. I'm Australian and have never heard it pronounced as anything but min-me. I'm happy to admit I could be wrong though. 

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[Jake Kotevski]

I'll second Sean — have only ever pronounced it (or heard it pronounced) as Min-mee. But I have never met Ralph Molnar or visited the type locality/spoken to locals. 

Ph: +61 0449 758 160                           

ResearchGate: Jake Kotevski

Instagram: theropods_down_under       

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From: dinosaurma...@googlegroups.com <dinosaurma...@googlegroups.com> on behalf of Sean McKelvey <smc...@gmail.com>
Sent: Saturday, January 17, 2026 9:46 AM
To: DinosaurMa...@googlegroups.com <DinosaurMa...@googlegroups.com>
Subject: Re: [DMG] Patagopelta new remains + Nopcsaspondylus as rebbachisaurid + dinosaur tracksites from Jurassic of Morocco

 

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[Stephen Poropat]

Alex Cook (who, like Molnar, is a former curator of Queensland Museum) also always pronounces it Min-my. I more often than not forget this and call it Min-me; old habits die hard. 

Dr Stephen F. Poropat

Deputy Director

Western Australian Organic and Isotope Geochemistry Centre

School of Earth and Planetary Sciences

Curtin University

Bentley, Western Australia

Australia 6102

https://stephenporopat.weebly.com/

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[Sean McKelvey]

Interesting, and duly noted. You learn something new everyday. More than likely I'll continue to pronounce it Min-me out of habit as well.

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[Mickey Mortimer]

"Lucas N. Lerzo (2026)
The lost fossil of the first discovered rebbachisaurid: reassessment of Nopcsaspondylus alarconensis (Diplodocoidea, Sauropoda)

...

The reassessment of Nopcsaspondylus does not find any diagnostic character which allows to recognise as a distinct species of rebbachisaurid. In addition, the erection of Nopcsaspondylus did not follow certain recommendations of the International Code of Zoological Nomenclature (ICZN), allowing to determinate that Nopcsaspondylus represents a nomen dubium"

Now that I have read the paper, Lerzo didn't find any autapomorphies, but he did note a unique combination of characters that distinguishes Nopcsaspondylus- 

"It seems to have a well development, as in some of the middle to posterior dorsal vertebrae of the specimen MMCh-PV 49, unlike to the Euro-African rebbachisaurids, such as Nigersaurus, Demandasaurus and Rebbachisaurus, in which the pleurocoel does not occupy most of the lateral surface of the centrum."

"The neural spine is short as in Nigersaurus (pers. observ; Sereno et al., 2007) but different from Rebbachisaurus and the South American rebbachisaurids, such as Limaysaurus, Katepensarus and specimen MMCh-PV 49, where the neural spine is high."

And since both MMCh-PV 49 and Nigersaurus have basically complete dorsal columns (two more anterior dorsals missing in the former) and were both personally examined by Lerzo, we know that there wasn't much positional variation in Nigersaurus' pleurocoel size or MMCh-PV 49's neural spine height. So there you go. Maybe Lerzo's wrong, but his words have Nopcsaspondylus showing a unique combination of characters.

As for being a nomen dubium based on the ICZN, the Code has no bearing on how diagnostic a taxon is. Lerzo's argument instead would seem to be designating Nopcsaspondylus a nomen nudum, but the only parts of the ICZN he argues Apesteguia didn't meet when naming the taxon are Recommendations (73B, 73C[.1, .2 and .10], 73C.6, 73G, 73J) not Articles. They're just best practice, not rules that must be followed for a taxon to be valid.
And for what it's worth (which is very little, since they are not binding rules), I don't think Apesteguia failed 73C.10 ("the geological age and stratigraphical position of the holotype") just because he seems to have gotten it wrong. 

Also, Lerzo seems to have misunderstood 73J, which he cites as "The author should also provide a complete list of diagnostic characters" and says "Nevertheless, the diagnosis does not present any autapomorphic traits for this taxon, not even at the time of its original erection." But that's Article 13.1.1 ("be accompanied by a description or definition that states in words characters that are purported to differentiate the taxon"), and Apesteguia DID provide a three character diagnosis that was supposed to distinguish the taxon, even if Lerzo thinks the characters don't work. 73J actually says "When establishing a new species-group taxon without a preserved name-bearing type, the author should provide extensive documentation (e.g., multiple original high-resolution images, DNA sequences, etc.) of potentially diagnostic characters as completely as possible", which Apesteguia admittedly did not do (citing Nopcsa's 1902 paper and incorrectly his own Figure 2 which only illustrates another unnamed rebbachisaurid dorsal).

So in conclusion, Nopcsaspondylus is a nomenclaturally valid taxon and seems to possess a unique combination of characters, pending further studies.

Mickey Mortimer

[Jaime Headden]

>  So there you go. Maybe Lerzo's wrong, but his words have Nopcsaspondylus showing a unique combination of characters.

Unfortunately, there's a not-insignificant group of researchers who argue that there must be autapomorphies, and not "unique combination of characters," which has resulted in the suppression and "diminution" of taxa into "nomina dubia," but also a very intense effort at overstating or overdefining variation as "unique" such as (by way of hypothetical example) the relative level at which two lamina on the dorsal neural arch converge. It can be technically right by quantification, without being qualified. "No other sauropod dorsal 2 has a conjunction of the ADPL with the PDPL this high!"

Now that's a bit exaggerated, but it's come up a few times in the diagnoses of various taxa, and worse it comes out from sauropods in which what amounts to miniscule and what should be plastic variation resulting from pneumatic/bone interactions with potential size-dependent variation (excavations in the vertebrae relating to weight reduction, perhaps) becoming treated as not merely specific variation, but *generic*. Everyone's genericometer goes haywire when it comes to sauropods, leading to unbounded high variation in sauropods from relatively under-sampled formations, all of them qualified by variously bulging protuberances or positional variation along the caudal series, etc.. It reminds me too much of shark and mammal molar systematics (with the caveat that mammalogists tend to put less emphasis on other teeth, and even less so on non-molariform molars, such as carnassials, because of the ... well: cusps and lophs get treated like lamina in sauropod dorsals).

So at the end of this, a whole paper that comes down to "we could tune our genericometer off unique combinations, and it doesn't occur to us that we should evaluate that methodology."

Cheers,

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--

Jaime A. Headden

The Bite Stuff: http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth" - P. B. Medawar (1969)