Your Friends The Titanosaurs: Mesetasaurus protector (plus news from Antarctica)

The newest titanosaur is the second from Uruguay and the Guichón Formation. Here's the breakdown:

Genus and Species: Mesetasaurus protector. The genus name is a reference to the locality, Meseta de Artigas. The species name is a reference to the Uruguayan national hero José Artigas, (Soto Núñez et al. 2026). His name is also part of the locality, so we end up with a multilayered reference that boils down to "José Artigas's lizard".

Citation: Soto Núñez, M., F. Montenegro, and D. Perea. 2026. A new aeolosaurini (Sauropoda, Titanosauria) from the Upper Cretaceous of Uruguay. Ameghiniana (advance online publication). doi: https://doi.org/10.5710/AMGH.19.06.2026.3689

Geography and Stratigraphy: The type and only known specimen is from Meseta de Artigas, in the northern part of Paysandú Department, Uruguay. We are in the Guichón Formation, previously noted as the source of the titanosaur Udelartitan celeste (Soto et al. 2024). At that time, an age in the first half of the Late Cretaceous was suggested. This time a somewhat younger age is proposed, "perhaps late Santonian-early Campanian" (Soto Núñez et al. 2026).

Holotype: FC-DPV 3740 (Vertebrate Fossil Collection, Facultad de Ciencias, Universidad de la República), two anterior caudals (Soto Núñez et al. 2026). The authors refer to the more anterior caudal as 3740A and the more posterior as 3740B, and suggest A is the third caudal and B is the sixth.

The two caudals are well-preserved, although unfortunately this is not the same as completeness (the processes are truncated). They are distinct from those of U. celeste, being decidedly aeolosaurine/id/inid in anatomy. They are also somewhat smaller, not that U. celeste was an especially titanic titanosaur in the first place. Not surprisingly given its anatomy, M. protector plots among the aeolosaurs, making it the second record of an Uruguayan aeolosaur after the Asencio Formation caudal in Soto et al. (2022).

I don't have a whole lot to say about this species. To make this post a little less perfunctory, I'd like to go a little farther south. Barrett et al. (2026) have reported the second titanosaur from Antarctica, after the caudal reported by Cerda et al. (2011, 2012). The new material is BAS D.8621.25 (British Antarctic Survey, Cambridge, United Kingdom), a partial anterior caudal that coincidentally enough also has a bit of an aeolosaur appearance. It comes from the early Campanian-age Beta Member of the Santa Maria Formation on James Ross Island. (For those of you keeping track, Cerda et al. also described their specimen, a partial middle caudal, from the Santa Maria Formation. The particular strata have since been placed in the overlying Snow Hill Formation as the Gamma Member.) It is not well preserved and is rather small, at only 59 mm (2.3 in) long, 89 mm (3.5 in) if you include the substantial posterior condyle. This puts it in the company of Magyarosaurus dacus. We can't be sure of the exact growth stage, but there's enough of the neural arch to show it wasn't a very young juvenile. Interestingly, although not described until now, BAS D.8621.25 is actually the first classic dinosaur fossil collected from Antarctica, way back in December 1985 (Barrett et al. 2026).

Several views of BAS D.8621.25. Figure 3 in Barrett et al. (2026). CC-BY-4.0.

References

Barrett, P. M., P. D. Mannion, S. L. Beeston, M. C. Lamanna, B. Clark, A. Otero, J. P. O’Gorman, and M. Evans. 2026. A titanosaurian sauropod dinosaur from the Upper Cretaceous of Antarctica. Acta Palaeontologica Polonica 71(2): 349–362. doi: https://doi.org/10.4202/app.01315.2025.

Cerda, I., A. Paulina Carabajal, L. Salgado, R. Coria, and J. J. Moly. 2011. The first record of sauropod dinosaurs from Antarctica. Journal of Vertebrate Paleontology, Program and Abstracts, 2011:86.

Cerda, I. A., A. Paulina Carabajal, L. Salgado, R. A. Coria, M. A. Reguero, C. P. Tambussi, and J. J. Moly. 2012. The first record of a sauropod dinosaur from Antarctica. Naturwissenschaften 99:83–87. 

Soto, M., F. Montenegro, F. Mesa, and D. Perea. 2022. Sauropod (Dinosauria: Saurischia) remains from the Mercedes and Asencio formations (sensu Bossi, 1966), Upper Cretaceous of Uruguay. Cretaceous Research 131:105072. doi: https://doi.org/10.1016/j.cretres.2021.105072. 

Soto, M., J. L. Carballido, M. C. Langer, J. C. G. Silva Junior, F. Montenegro, and D. Perea. 2024. Phylogenetic relationships of a new titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Uruguay. Cretaceous Research 105894. doi: https://doi.org/10.1016/j.cretres.2024.105894.

Soto Núñez, M., F. Montenegro, and D. Perea. 2026. A new aeolosaurini (Sauropoda, Titanosauria) from the Upper Cretaceous of Uruguay. Ameghiniana (advance online publication). doi: https://doi.org/10.5710/AMGH.19.06.2026.3689.

Your Former Friends The Ex-Titanosaurs

If you frequent The Compact Thescelosaurus, you may have noticed that several sauropods formerly placed in Titanosauria have been reclassified. (Apropos of nothing, I often wonder what the people who are browsing the sheets think when they see me active. Do they get excited to see what I'm working on? Or is it an inconvenience to whatever searching or sorting they're doing? Sometimes more appear while I'm working. I know it's just a coincidence, but it amuses me to think there's some kind of alert I don't know about that is issued when I show up.) This is not the first time this has happened. Back in 2019 Mannion et al. (2019) led me to move Baotianmansaurus henanensis and Dongyangosaurus sinensis to Titanosauria? (the question mark, the second-to-last refuge of a coward) and Jiangshanosaurus henanensis and Yongjinglong datangi out of Titanosauria altogether. After Beeston et al. (2024), the diamantinasaurs were also put at Titanosauria?. There has now been another purge of Early Cretaceous forms following Mannion and de Souza Carvalho (2026).

(Wait a second... Mannion et al. 2019, Mannion and de Souza Carvalho 2026, Mannion as third author on Beeston et al. 2024... Philip Mannion, stop taking my titanosaurs!)

In this case, the affected species were Hamititan xinjiangensis, Ninjatitan zapatai, and Volgatitan simbirskiensis. Although from different continents and formations, all three share one key characteristic: Supposed Early Titanosaur. SET is almost a curse. As soon as someone starts thinking a particular sauropod represents an Early Titanosaur, it is liable to transform, as if by perverse magic, into something else, and I don't recall that any have actually gotten back to being classified as titanosaurs. The main culprit seems to be that we just don't really have a good grasp on what somphospondyls were up to in their early years. (Well, that and the inevitability that the closer you get to the base of any lineage, the more generalized the taxa. And, perhaps, sometimes people might get too enthusiastic hoping for an Early Titanosaur and read a bit more into specimens than is warranted.) Somewhere in there is the lineage that led to titanosaurs, but until they established their monopoly, it's difficult to distinguish that thread from various also-rans, plus other sauropod groups that may be confused with them when you only have a couple of bones.

Backing up for a moment, Mannion and de Souza Carvalho (2026) is not primarily about reclassifying three disparate Early Cretaceous titanosaur-like sauropods. It's actually a redescription of Triunfosaurus leonardii, another victim of SET. In a minor upset for how these descriptions usually go, the type material doesn't turn out to be chimeric (the "middle-posterior caudals" are more likely anterior, but that's about as close as it gets to major anatomical reinterpretation). This then turned into an opportunity to look at the relationships of five SETs: T. leonardii, the three mentioned above, and Tengrisaurus starkovi. Running equal weighting (EQW) and extended implied weighting (EIW) against their data, they found the following placements:

• Hamititan was a turiasaurian under EQW and deeply nested in Titanosauria as a saltasauroid under EIW, which is a good trick. The authors in passing noted issues with its diagnosis and suggested it is not diagnostic at the genus level. For our purposes, I took the lowest common denominator and reassigned it to Eusauropoda.
• Ninjatitan was a diplodocid under EQW and a non-titanosaurian somphospondyl under EIW, hanging out with Chubutisaurus insignis. It isn't entirely comfortable in either position, and diplodocoids are known from the same formation, so the scrappy type could be chimeric and include both (Mannion and de Souza Carvalho 2026). For our purposes, I reassigned it to Neosauropoda.
• Tengrisaurus, boringly, was a clean titanosaur either way, although of course its exact placement in Titanosauria varied. No change was needed, and at the moment it is our oldest named titanosaur by default. Congratulations.
• Triunfosaurus was a non-titanosaurian somphospondyl under EQW and a basal titanosaur under EIW. Essentially it was either just inside or just outside the velvet rope, so hopefully that means there's a pretty good handle on it. No change was needed, as I already had it at Somphospondyli.
• Finally, Volgatitan was quite consistent... consistently a mamenchisaurid, which the authors found somewhat puzzling and not supported by the most robust of characters. A type specimen consisting of seven partial caudals also did not inspire great confidence in the results. Nevertheless, I moved it to Eusauropoda (I'm not using Mamenchisauridae until someone determines what Mamenchisaurus is and isn't).

Of these five, the two with the best cases to be recognized as true Early Titanosaurs are Tengrisaurus, which always ended up within it, and Triunfosaurus, on the doorstep. Although it's tempting to take one and plant a flag for the origin of the group, the situation is too messy for anything that neat, as noted by Mannion and de Souza Carvalho (2026). There's almost no record of somphospondyls in the Late Jurassic and earliest Cretaceous, when by definition they must have been around (because their sister group Brachiosauridae was around), and when we do start seeing them, they're all over the place (Mannion and de Souza Carvalho 2026).

References

Beeston, S. L., S. F. Poropat, P. D. Mannion, A. H. Pentland, M. J. Enchelmaier, T. Sloan, and D. A. Elliott. 2024. Reappraisal of sauropod dinosaur diversity in the Upper Cretaceous Winton Formation of Queensland, Australia, through 3D digitisation and description of new specimens. PeerJ 12:e17180. doi: 10.7717/peerj.17180.

Mannion, P. D., and I. de Souza Carvalho. 2026. Re-evaluation of the Early Cretaceous titanosauriform sauropod dinosaur Triunfosaurus leonardii from the Triunfo Basin, Brazil: implications for the initial radiations of Somphospondyli and Titanosauria. Zoological Journal of the Linnean Society 207(1): zlag073. doi: 10.1093/zoolinnean/zlag073.

Mannion, P. D., P. Upchurch, X. Jin, and W. Zheng. 2019. New information on the Cretaceous sauropods of Zhejiang Province, China: impact on Laurasian titanosauriform phylogeny and biogeography. Royal Society Open Science 6(8):191057. doi: 10.1098/rsos.191057.

Your Friends The Titanosaurs: Phosphatotitan khouribgaensis

The latest friendly titanosaur to come along hails from Morocco, making it the first named Moroccan titanosaur but not the first record. Other occurrences are mentioned here. For some reason it seems like the new names are always specimens that weren't included. Still lots of titanosaurs out there!

Your Friends The Titanosaurs: Yeneen houssayi

What do you get the formation that has five established titanosaur species and a couple of ne'er-do-wells? A sixth titanosaur, of course!

All joking aside, it's misleading to think of "Titanosauria" as a relatively small-scale group like Diplodocidae or Brachiosauridae when it's really a massive, sprawling complex including multiple distinct lineages that essentially monopolized all things sauropod in the Late Cretaceous. We talk of the Morrison Formation having diplodocids and dicraeosaurids and camarasaurids and brachiosaurids and whatever else, and that may sound more impressive than the Bajo de la Carpa Formation having six different titanosaurs. "What? You need all those titanosaurs?" "All those titanosaurs" are functionally replacing each of those smaller clades of the Morrison, as well as apparently just about everything else large and herbivorous. It's just the relationships and smaller divisions are still fuzzy. Eventually, we'll have a better grasp. But enough philosophy! Let's bring on today's guest, Yeneen houssayi. (And thank you to Alberta Claw and Stephen Poropat for supplying me with the paper!)

Your Friends The Titanosaurs: Utetitan zellaguymondeweyae

Back almost four years ago when we first waded into Alamosaurus, I noted that "I was waiting on it because I was concerned that it might suffer a taxonomic detonation at any time, so I thought I'd hold off as long as possible." Titanosaurs work on their own schedule. Although people have danced around the issue for decades by suggesting that A. sanjuanensis is dubious or refraining from including some specimens in the species, nobody had taken the step of formally proposing another name for any of the material until Gregory S. Paul in October 2025 with Utetitan zellaguymondeweyae. This genus and species are based on the North Horn specimen that has long been the "practical purposes" type* of A. sanjuanensis.

*Seems like there ought to be a name for non-type specimens that everyone uses instead of the type. "Apatotype", for "deceptive type"? Or "pseudotype" for "false type"? Think like the "Mantel-piece" of Iguanodon mantelli. Brachiosaurus had a whole apatotype species until it was split off for Giraffatitan.

Feeding Diamantinasaurus

It's no secret that we like titanosaurs here at Equatorial Minnesota, and another favorite topic is potential gut contents in herbivorous dinosaurs (albeit we don't see a lot of papers on it). When Poropat et al. (2025)'s paper on the potential gut contents of a specimen of Diamantinasaurus matildae came out a couple of weeks ago, it was an obvious paper to cover here. True, diamantinasaurus may not be titanosaurs by phylogeny, but they're close, and they're still titanosaurs in our hearts.

Titanosaur osteoderms, 2025 update

Occasionally I glance at the site statistics, but since I don't use anything detailed there's not a lot to get from them except that it's fun to see where the obvious spoof hits are coming from (Singapore, lately; sometimes Hong Kong or Russia). Sometimes I can tell that a post has been picked up elsewhere and gotten a few views. Over the last month or so, there have been an unusually large number of visits to "Titanosaur osteoderms: functions and conclusions", and at the same time a similar number of visits have come from a service at the University at Buffalo. Conclusion? Seems like someone at the university is using the post in a course. If that's what's going on, this one is for you!

Since I wrote the osteoderm series back in 2019, there have a few reports of interest on titanosaur osteoderms. I added several overlooked and new records to the distribution post in 2019–2020, and there hasn't been much change there since. One tangential note, also applicable to "Titanosaurs of Yesterday", is a further advance in the study of Agustinia ligabuei, the spiky sauropod that wasn't. Bellardini et al. (2022) published an analysis that found A. ligabuei was not a titanosaurian or even a macronarian, but a rebbachisaurid. (And it's still not armored, either.)

As noted in the Menucocelsior arriagadai post, Rolando et al. (2022) was not just a description of a new titanosaur taxon, but also included reports of material from other titanosaurs. Among these specimens were four isolated osteoderms from the Cerro Matadero site of the Allen Formation. Three represent the "ellipsoidal" form (bulb-and-root) of D'Emic et al. (2009) and the other is a "keeled" osteoderm. Rolando et al. interpreted the keeled osteoderm as perhaps from the tail or back of a saltasaur and the two more complete ellipsoidal osteoderms as perhaps aeolosaur osteoderms from the hip region.

Another report also discussed in another post is Fronimos (2021) on an osteoderm of a Big Bend titanosaur (e.g., Big Bend Alamosaurus). To paraphrase, this is a large oval and unkeeled osteoderm from the upper Javelina. It is tall, symmetrical, 19.9 cm long (7.83 in), not hollow, not differentiated into a bulb and root, and does not have a cingulum. It resembles the North Horn Formation Alamosaurus osteoderm and the osteoderms of Mendozasaurus neguyelap and unnamed South American forms (Fronimos 2021). Fronimos (2021) regarded the most likely functions as mineral storage, local defense, and display.

Concerning the function of titanosaur osteoderms, Silva Junior et al. (2022) published a study using finite element analysis to evaluate titanosaur osteoderms versus likely titanosaur adversaries, specifically the bites of abelisaurs and baurusuchid crocs. They found that bites had less of an effect on solid osteoderms (i.e., those without hollow internal spaces), and interpreted this to indicate that solid osteoderms could do more than provide mineral storage. On the other side of the mineral storage question, Broeckhoven and du Plessis (2022) made an analysis of osteoderms in armadillo lizards. Using micro-computed tomography, they found that the female lizards in their study had denser, more compact osteoderms than males, and observed the presence of TRAP-positive cells (tartrate-resistant acid phosphatase, involved in bone resorption and breakdown). Denser osteoderms may help maintain a minimum level of mineral density for reproduction and provide defensive strength to osteoderms also being used for a mineral storage function. The authors did not find a difference in density between seasons, and suggested this meant the osteoderms were only subject to resorption during particularly stressful conditions, or that it only took place during certain phases of embryo growth. They concluded that mineral storage for reproduction is a plausible function for osteoderms in female reptiles.

Finally, I've saved the most interesting update for last. In an abstract, Filippi et al. (2023) described an articulated tail, MAU-Pv-CO-726, from the Bajo de la Carpa Formation of Cerro Overo–La Invernada, Patagonia, Argentina. (Yes, another Bajo de la Carpa mystery titanosaur!) MAU-Pv-CO-726 includes 25 caudals, 11 chevrons, and two osteoderms in place, with another nearby. The pair of osteoderms is associated with the last anterior caudal, found flanking the side and underside of the tail (about where the chevron articulates with the caudal). They are described as bulbous, oval, a little more than 10 cm (4 in) long, and feature a medial ridge and tapered spine on the lateral half, whereas the solitary osteoderm is described more like a classic bulb-and-root. Filippi et al. found MAU-Pv-CO-726 to be the sister taxon of Rinconsaurus caudamirus, marking the first evidence of an armored rinconsaur (and no doubt causing R. caudamirus's usual best friend Muyelensaurus pecheni great phylogenetic distress). They interpreted the location of the osteoderms as evidence of a defensive function. The osteoderms' placement also has implications for paleoart; titanosaur restorations usually put osteoderms on upper-lateral surfaces. But, then again, if you want my opinion I think titanosaurs were too diverse for a one-size-fits-all approach to osteoderms, in function, anatomy, or placement.

References (note that a couple are different from previous usage, as those were online preprints)

Bellardini, F., R. A. Coria, G. J. Windholz, A. G. Martinelli, and M. A. Baiano. 2022. Revisiting the Early Cretaceous sauropod Agustinia ligabuei (Dinosauria: Diplodocoidea) from southern Neuquén Basin (Patagonia, Argentina), with implications on the early evolution of rebbachisaurids. Historical Biology 35(12): 1–27. doi: https://doi.org/10.1080/08912963.2022.2142911

Broeckhoven, C., and A. du Plessis. 2022. Osteoderms as calcium reservoirs: Insights from the lizard Ouroborus cataphractus. Journal of Anatomy 241(3): 635–640. doi: https://doi.org/10.1111/joa.13683

D'Emic, M. D., J. A. Wilson, and S. Chatterjee. 2009. The titanosaur (Dinosauria: Sauropoda) osteoderm record: review and first definitive specimen from India. Journal of Vertebrate Paleontology 29(1):165–177.

Filippi, L. S., F. Bellardini, A. Paulina-Carabajal, P. Cruzado-Caballero, J. González-Dionis, A. H. Méndez, F. Gianechini, K. Ulloa-Guaiquin, A. Garrido, I. Maniel, Y-N. Lee, and K. Do-Kwon. 2023. Articulated osteoderms on a titanosaur tail from Cerro Overo–La Invernada (Bajo de la Carpa Formation), Upper Cretaceous, Northern Patagonia Argentina: Paleobiological and paleoecological implications. Publicación Electrónica de la Asociación Paleontológica Argentina 24(R3): R67–R68.

Fronimos, J. A. 2021. Morphology and neurovascular anatomy of a titanosaur (Dinosauria, Sauropoda) osteoderm from the Upper Cretaceous of Big Bend National Park, Texas. Cretaceous Research 120: 104670. doi: https://doi.org/10.1016/j.cretres.2020.104670

Rolando, M. A., J. A. Garcia Marsà, F. L. Agnolín, M. J. Motta, S. Rozadilla, and F. E. Novas. 2022. The sauropod record of Salitral Ojo del Agua: An Upper Cretaceous (Allen Formation) fossiliferous locality from northern Patagonia, Argentina. Cretaceous Research 129: 105029. doi: https://doi.org/10.1016/j.cretres.2021.105029

Silva Junior, J. C. G., F. C. Montefeltro, T. S. Marinho, A. G. Martinelli, and M. C. Langer. 2022. Finite elements analysis suggests a defensive role for osteoderms in titanosaur dinosaurs (Sauropoda). Cretaceous Research 129: 105031. doi: https://doi.org/10.1016/j.cretres.2021.105031

Your Friends The Titanosaurs: Chadititan calvoi

No sooner do I finish one titanosaur post when another new one shows up for its turn in the spotlight. Our latest guest, Chadititan calvoi, is another from the hallowed titanosaur stomping grounds of Late Cretaceous Patagonia. For anyone who feels the need to chuckle over the meme factor in the name, the jump break should present an opportunity to get it out of the system. (Ironically enough, Chadititan is noted for its small body size and slender limbs.) If you don't know the meme, feel free to ignore it and cross the jump break just the same.

Your Friends The Titanosaurs: Petrustitan hungaricus and Uriash kadici (and every other Transylvanian titanosaur)

It's been a while since I got to do one of these...

To say that Díez Díaz et al. (2025) names Petrustitan hungaricus and Uriash kadici is to miss the point. Between the paper itself and the supplementary material, you get a novel's worth of information on the titanosaurs of Romania, including descriptions of a couple dozen significant finds (including individuals and assemblages of multiple individuals). But yes, the report does name one new genus and species, and transfers another species to a second new genus.

Your Friends The Titanosaurs: Qunkasaura pintiquiniestra

2024 has been a great year for new titanosaurs, as we are now on the fifth to be announced and we're still more than three months from the end of the year. For a change of pace, this time we're heading to Europe. Qunkasaura pintiquiniestra, the first new European titanosaur in more than two and a half years, hails from the Lo Hueco site in Spain.

Your Friends The Titanosaurs: Tiamat valdecii

I've been remiss in getting to our latest titanosaur, in part because I was busy with other projects and in part because it took a while to get a copy of the paper. A side visit to the University of Michigan library system after conference hours solved the second issue, so without further ado I present Tiamat valdecii.

Diamantinasaurs, and being or not being a titanosaur

It's not all about new taxa with titanosaurs here. There are always publications on other topics; it might be fun to do a roundup feature every so often. Anyway, I thought I'd catch up on the Australian branch of the tree, as well as the eternal question of just what is a titanosaur, after all.

Your Friends The Titanosaurs: Titanomachya gimenezi

2024 has been productive for titanosaurs. Not counting other titano-centric publications, there have already been (potentially) three new genera and species. For number 3, we head back to the familiar land of Patagonia in Argentina, although in this case our new guest represents an Upper Cretaceous formation with no previous named titanosaurs (which seems like a real oddity these days). Titanomachya gimenezi is also decidedly non-titanic for a titanosaur, hanging out down in the saltasaur neighborhood.

Your Friends The Titanosaurs: Udelartitan celeste

Today's new entrant is actually a former briefly featured coming attraction coming off the board, the fourth such coming attraction to have arrived. It is also the first classic dinosaur to be named from Uruguay, which is the first new country added since Ecuador with Yamanasaurus lojaensis a few years back. (2020 if you insist on paper, 2019 if you just want to get it over with. Also, of course, that was a titanosaur too!) So, with that introduction, we welcome Udelartitan celeste.

Your Friends The Titanosaurs: Gandititan cavocaudatus?

Here we are, already through January of 2024, and clearly we are not starting out like 2023, where the entire month had nary a new dinosaur. Today's entrant was the third of five announced in January 2024 (a couple of weeks ago, actually). You may notice the question mark in the post title; although described as a basal titanosaurian, Gandititan cavocaudatus fits a certain "type" of sauropod (mid-Cretaceous East Asian titanosauriform) that delights in phylogenetic instability. This to me is a subtle signal that something is going on we don't understand yet, so I'd best hedge my bets. So, maybe it's a titanosaur, maybe it isn't, but at any rate it's worth an introduction.

Your Friends The Titanosaurs: Bustingorrytitan shiva

In terms of dinosaurs, 2023 is going to go out like it came in: with a new plus-sized Huincul Formation titanosaur. This one has been delivered just in time for Christmas, although it's unlikely to fit under anyone's tree. Of course, there have been some comments that it is not as big as has been published, but regular readers will know not to get too wrapped up in these things.

Your Friends The Titanosaurs: Inawentu oslatus

Our latest guest in the series is Inawentu oslatus from the middle Late Cretaceous of Argentina. I. oslatus is more than your average new titanosaur; it is one of the two major unnamed titanosaurs discussed a couple of years back, MAU-Pv-LI-595. This is the more recently discovered of the two skull-bearing titanosaurs from Rincón de los Sauces (the other is MAU-Pv-AC-01).

Your Friends The Titanosaurs: Jiangxititan ganzhouensis

It's that time again, when another titanosaur makes an introduction. Today we have Jiangxititan ganzhouensis, from the late Late Cretaceous of southeastern China. As a disclaimer, I tend to reserve my judgment with East Asian titanosauriforms, who have a tendency to play coy about their phylogenetic relationships. However, J. ganzhouensis is interesting on its own terms, whether or not it is within that charmed circle of "Andesaurus delgadoi + Saltasaurus loricatus".

A lateral view of the type vertebrae of Jiangxititan ganzhouensis, dorsals on left, cervicals on right; scale is 20 cm (8 in) (Figure 3, Mo et al. 2023, which see for legend) (CC BY-NC-ND-4.0).

Your Friends The Titanosaurs: Igai semkhu

This happens to be the 400th post on Equatorial Minnesota, and it's on a fitting subject, as about 15% of the posts have been on titanosaurs. In fact, this particular titanosaur has been mentioned before, as a potential coming attraction. What was referred to as MB.R.Vb-621–640 in that post now has a name: Igai semkhu. Let's have a look at what this new genus and species can tell us.

Figure 1 from Gorscak et al. (2023), including quarry map (with lost material), reconstruction, and geographic insets (CC BY-NC-ND-4.0).

The Face of Diamantinasaurus (and some other body parts)

One of the things that was frequently missing from "Your Friends The Titanosaurs" was heads. Sure, there were a fair number of lower jaws and braincases, but actual faces were few and far between. Skulls just don't seem to have stuck with the rest of the skeleton, and in general were not made of the sternest material in a titanosaur's body. (Bitey parts of the skull, yeah, those are more robust. Braincases, yeah, those are knots of bone. Stuff in between? Not so much.) Several entire continents are unrepresented by reasonably complete titanosaur skulls. We can now scratch Australia off that list, thanks to Diamantinasaurus matildae, as described in great detail by Poropat et al. (2023).

(...or can we? See below!)