PNSO debuts on the market in 2016 with images of five models: Shantungosaurus, Mandschurosaurus, Lufengosaurus, Euhelopus and Huanghetitan. Of these five original PNSOs, the largest is undoubtedly Huanghetitan. Some would say it’s appropriate, being Huanghetitan a titanosauriform, the clade to which belong the largest – but also the smallest – sauropods. The Titanosauriformes, in fact, are a group with an enormous geographical and temporal diffusion, having been found in all continents and in rocks ranging from the middle Jurassic to the end of the Cretaceous. A good half of the known sauropods are classified as titanosauriformes, and a similar variety of species must have corresponded to an equal variety of morphs and ecologies. Too bad that most of the remains are fragmentary and that many species are classified on the basis of the vertebral laminae: an undoubtedly diagnostic character (among sauropod species, vertebral laminatae are more or less like fingerprints among individuals of Homo sapiens) , but not very useful one for reconstructing its appearance in life. Huanghetitan was cursed too with fossil incompleteness and, as we’ll see, getting an idea of what it looked like may be incredibly difficult.
The genus Huanghetitan was established in 2006 (You et al.) with the type species H. liujiaxiaensis. In 2007, a second species was described, “H.” ruyangensis Lu et al. 2007 – the quotation marks mean that other analyzes indicated that this species is not sister to H. liujiaxiaensis and therefore should be assigned to a new genus (Mannion et al. 2013). The phylogeny of titanosaurs rests on a delicate balance, but the analyzes in which Huanghetitan appeared more or less agree that it belongs to the mess of non-titanosauriforms (it’s right outside of Titanosauria in Averianov et al. 2017). Both species are rather incomplete (two caudals, the sacrum, fragments of the ribs and one scapula for H. liujiaxiaensis, the sacrum, the first ten caudals, some ribs and hemi arches and part of the ischium “H.” ruyangensis), but we can reconstruct this animal from related species, right? Well, here is where the problem arises: the most complete somphospondylan (the group immediately outside Titanosauria) is, without doubt, Euhelopus: too bad that in a recent analysis (Moore et al. 2020) this particular genus decided to pack up and cross the family tree to return in the company of Mamenchisaurus and Omeisaurus (among which it was classified in the 20th century), leaving us with wery little to work. So in this review we’ll treat the PNSO model more or less as a generic titanosaur.
The problems in restoring a sauropod begin right from the skull: comparatively small compared to the body and lightened by fenestrae, it’s one of the most fragile parts of a sauropod skeleton, to a level that to the day we know the skull of only five species of titanosaurus: Nemegtosaurus , Rapetosaurus, Tapuiasaurus, Bonitasaura and Sarmientosaurus. The shape of the model’s skull, reminiscent of a hybrid between that of a basal macronarian (like Brachiosaurus) and that of a diplodocid, and narrowing before the eyes when seen fron above (a trait that makes it look similar to an “8”), is reminiscent of the skull of Nemegtosaurus, Tapuiasaurus and Rapetosaurus, with deep jaws and mandibles and teeth limited to the anterior portion of the muzzle, giving the skull a characteristic profile (the “8” shape represents an adaptation to increase the size of the mouthful that can be collected at each bite). While the skulls of Tapuiasaurus and Nemegtosaurus are quite similar to each other, Rapetosaurus has a lower skull, more posteriorly extended teeth and a huge anteorbital window, but once covered with a conservative integument (speculation about the presence of baloons and other soft tissue structures is free) these three titanosaurs are not that different from each other. The most suitable skull to reconstruct Huanghetitan would probably have been that of Sarmientosaurus, which occupies a more basal position and is intermediate between “nemegtosaurids” and macronarians such as Brachiosaurus, but this animal was only described in 2016 – too late for PNSO.
The teeth are covered by structures alike to lips and are not visible, while the nostrils are in the appropriate position, near the tip of the muzzle: although the nasal openings of the titanosaurs were set back – probably an adaptation to reinforce the anterior part of the skull, now made of solid bone – their position (as shown in Witmer, 2001) does not correspond to that of the external nostrils. Unlike the other four original PNSOs, the skull shows little sign of shrinkwrapping, with a lower jaw directly connected to the neck via the muscles (relatively robust in comparison to other sauropods). The eyes are painted metallic gold, as in the famous Carnegie line, and – an interesting touch – the pupil appears to be horizontal: it’s a common trait in many modern grazing mammals, because it allows a greater perception of danger while the animal is feeding. , but we cannot know if it was also a trait of sauropods, since no modern (or extinct) mammal forages at their height. I also specify that it could be, rather than speculation, an error due to a hasty painting in my sample.
No cervical from Huanghetitan is preserves so, like the skull, the length of the neck is also entirely speculative. If compared with PNSO Euhelopus, however, the model gives an impression of positive robustness: the neck is a massive structure, twice as wide as the skull; the vertebrae are not visible, but they can sometimes be distinguished by touch (not impossible , considering how big titanosaur cericals are). The base of the neck is covered by wrinkly skin, so much so that I wouldn’t rule out the presence of a seam, but it’s well hidden. Where the neck attaches to the body, the scapula can be guessed more by the differently oriented folds and colour than because it protrudes, with the exception of the dorsalmost part of the scapula itself. But even in modern quadrupeds such as elephants there is not much tissue in that position; mammals are never the best analogy for dinosaurs, but in this case the comparison doesn’t look too stretched. The barrel trunk is particularly robust: in many titanosaurs, in fact, the paracetabular process of the ilium protrudes outwards by almost 90 degrees, to provide greater anchor to the tendons that supported the abdomen. This results in titanosaurs having more spaced limbs than most sauropods.
The forelimbs are sturdy and column-shaped and the musculature, although present, is not exaggerated (as is in the Papo Brachiosaurus, which never skypped arm day). The hand is horseshoe shaped and it’s not possible to distinguish the fingers, with one exception: the first finger has a large claw, which is tought to be used for excavation and delivering dangerous kickes to predators. This claws is the legacy of Huanghetitan’s Triassic ancestors, bipeds with large, sickle-shaped claws in the first finger of the hand,which they kept when they transitioned to the quadrupedal gait. In the line that led to derived titanosaurs, however, it looks like that the claw was gradually reduced and the last Cretaceous titanosaurs, such as Opisthocoelicaudia, had not only lost their claws, but had given up their fingers altogether, thus walking on the metacarpal bones (the bones of which is composed the wrist). Huanghetitan is a primitive titanosauriform and therefore is not supposed to have adapted in such estreme ways: we have no hand bones, but the titanosaur Diamantinasaurus still shows the big claw, so its presence in the PNSO model is probably correct.
Unlike the forelimbs, sauropod hindlimbs were almost plantigrade, to better distribute the weight, and in Neosauropods they possessed three curved claws directed outward. And here is the problem: in the right foot, the PNSO Huanghetitan has four claws. In the left, three. Oversight of the sculptor? Willingness to represent a mutant specimen? I also found mention of a possible four-clawed footprints in the same province which Huanghetitan is from, but I was unable to track down the paper and thus the datation: it may not be a neosauropod. Along the hind limbs there are four seams, and I must say that, although not invisible, they are still less invasive and annoying than others.
The most invasive seam lies at the tail base. At least in my specimen, in fact, the two halfs do not match perfectly and there is like and unsculpted area a millimeter wide that runs around the whole animal. Thankfully, the size of the model helps, and at 70cm in length, one millimeter is easily ignored. About the tail, is it sturdy enough? The caudofemoral are never enough, but a certain effort has been made and you can see that in cross section the tail is almost round. At the base of the tail there is the cloaca, as always a detail that denotes attention. As for the length of the tail, it looks adequate.
Along with their size, Titanosaurs are also famous because they’re the only sauropods to have osteoderms (ossifications of dermal origin) embedded in the skin. Older readers surely remember the Saltasaurus illustrations from the 1980s-1990s, where it looks like it had skinned an ankylosaurus and wore its skin like Hercules. Fortunately, the PNSO model is more realistic: begining at the base of the neck, on the dorsal surface of the back, there is a mosaic of large osteoderms surrounded by smaller ones, highlighted by a clear wash that has slide into the space between one and the others (a bit like in the PNSO Ankylosaurus). The osteoderms are really well sculpted: they are not simple bumps, they looks like proper titanosaur skin. Now, we don’t know if Huanghetitan in particular had osteoderms (they might be exclusive to a particular titanosaur clade called Lithostrotia), but considering the model a generalized titanosaur they are certainly captivating. Bumps also run near the shoulder, pelvis and wrist, but – being not highlighted by washing – I can’t say if they’re suppoded to be osteoderms too, or just particularly large scales. In the areas free from osteoderms there is a dense mosaic of scales (probably too large, given that the largest sauropod scales are around 6 cm, but pleasing to the eye), as well as skin folds and ridges; particularly loose folds are found between the flank and abdomen and on the neck.
The painting – as you can see – is nothing too exciting: it’s better on the head and on the osteoderms, while the rest of the body is painted with a certain degree of approximation. It would not have hurt to extend the wash to the rest of the model, to bring out details (especially comparing the painting with the Huanghetitan maquette displayed at PNSO exibitions), but again its dimensions help in blending the pattern. How big is this Huanghetitan? The model is 69 cm long, but if you think it weights a ton, then recondiser: the PNSO Huanghetitan is made of vinyl and internally hollow – probably any big model in your collection (in example, one of the old Carnegie sauropods) is heavier. What scale is it? Well, it depends. If we consider it H. liujiaxiaensis, it is probably a 1:18 scale animal (Molina-Pérez and Larramendi, 2021 estimate this animal to be about 18 meters long). The estimates for “H.” ruyangensis vary wildly, from Paul (2019) assuming the same tonnage as Patagotitan, to the more conservative Molina-Pérez and Larramendi which instead downsized it to “only” 24 meters and more or less 30 tons, thus making the model more or less 1:25.
Ultimately, while we may not know how accurate this model is for Huanghetitan specifically, it remains one of the best depictions of a sauropod on the market and, due to the lack of knowledge we have of titanosaurs, it’s quite versatile and can represent other huge titanosaurs (eg. Argentinosaurus) in your collection. The model is currently retired, but it is still possible to find it on ebay or Aliexpress, from third-party sellers.
Cerda I.A.; Powell J.E. (2010) Dermal armor histology of Saltasaurus loricatus, an Upper Cretaceous sauropod dinosaur from Northwest Argentina Acta Palaeontologica Polonica 55 (3): 389-398
Hallett M.; Wedel M. The Sauropod Dinosaurs: Life in the Age of Giants. Baltimore, Johns Hopkins University Press, 2016. 336 pp
Lü J.; Xu L.; Zhang X.; Hu W.; Wu Y.; Jia S.; Ji Q. (2007). A New Gigantic Sauropod Dinosaur with the Deepest Known Body Cavity from the Cretaceous of Asia. Acta Geologica Sinica. 81 (2): 167
Martínez R.D.F.; Lamanna M. C.; Novas F. E.; Ridgely R. C.; Casal G. A.; Martínez J.E.; Vita J.R.; Witmer L.M. (2016). A Basal Lithostrotian Titanosaur (Dinosauria: Sauropoda) with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria. PLOS ONE. 11 (4): e0151661
Molina-Pérez R.; Larramendi A. Dinosaur Facts and Figures: The Sauropods and Other Sauropodomorphs. Princeton, Princeton University Press, 2020. 272 pp.
Moore, A.J.; Upchurch, P.; Barrett, P.M.; Clark, J.M.; Xing, X. (2020). Osteology of Klamelisaurus gobiensis (Dinosauria, Eusauropoda) and the evolutionary history of Middle–Late Jurassic Chinese sauropods. Journal of Systematic Palaeontology. 18 (16): 1299–1393
Paul, G. S. (2019). Determining the largest known land animal: A critical comparison of differing methods for restoring the volume and mass of extinct animals. Annals of the Carnegie Museum. 85 (4): 335–358
Ullmann P.V.; Bonnan M.F.; Lacovara K.V. (2017) Characterizing the Evolution of Wide-Gauge Features in Stylopodial Limb Elements of Titanosauriform Sauropods via Geometric Morphometrics. Anat Rec (Hoboken) 300(9):1618-1635.
Witmer L.M. (2001) Nostril position in dinosaurs and other vertebrates and its significance for nasal function. Science 293(5531):850-3.
You H.; Li D.; Zhou L.; Ji, Q. (2006). Huanghetitan liujiaxiaensis, a New Sauropod Dinosaur from the Lower Cretaceous Hekou Group of Lanzhou Basin, Gansu Province, China. Geological Review. 52 (5): 668–674.
The author would like to thank users Titanosaurus indicus, Prehistoric King and Cretaceous Barosaurine (fadeno) from the Sauropodomorpha Discord server for their contributions to this article.