PNSO has in its catalog an interesting offer of species from the Shaximiao formation (Middle/Late Jurassic of China): Yangchuanosaurus, Chungkingosaurus, the two versions of Mamenchisaurus, Tuojiangosaurus, and now “Sinraptor“, which has been a somehow divisive model since the first images. No surprise, since it represents a divisive animal by itself – starting with its name. The shape of the skull immediately identifies the PNSO model as “Sinraptor” hepingensis. If you are not interested in finding out more about its classification, you can click on the bar below and close the next paragraph, but you will remain curious about why I use quotation marks when talking about this species.
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The quotation marks mean that probably this animal did not belong to the genus Sinraptor: when it was unearthed, in 1985, it was first considered a new specimen of Yangchuanosaurus shangyuensis, and then classified (Gao, 1992) as a third species of Yangchuanosaurus, Yangchuanosaurus hepingensis (a second species, Yangchuanosaurus magnus, was established in 1983, but turned out to be a fully mature specimen of Y. shangyuensis). In the description of Sinraptor dongi (1994), it was found more closer to this genus and therefore moved from Yangchuanosaurus to Sinraptor. But is it really a Sinraptor? In 2012 the famous Carrano et al. Tetanurae phylogeny not only moved the English theropod Metriacanthosaurus in Sinraptoridae, which has since been called Metriacanthosauridae (because Metriacanthosaurus was described before Sinraptor), but also recognized the Thai theropod Siamotyrannus as the closest species to Sinraptor dongi and Metriacanthosaurus and hepingensis in polytomy (that is, on two branches equally distant) from them. Thus “Sinraptor” hepingensis cannot be called Sinraptor without including in Sinraptor also (surely) Siamotyrannus and (perhaps) Metriacanthosaurus. Why not Yangchuanosaurus, too? Because Yangchuanosaurus is part of the MetriacanthosauriDae, but not of the MetriacanthosauriNae, like tigers and lions are part of the FeliDae but not of the FeliNae (which instead include animals such as the house cat, the wild cat and the puma). The only way to save the “Sinraptor hepingensis” combination, and thus call the PNSO model Sinraptor, would be a new study finding that the hepingensis species is more closely related to Sinraptor dongi than Siamotyrannus is.
Now let’s see why this model is so divisive:
Since the publication of the first images, comparisons with the Indominus Rex from Jurassic World and Skull Island’s fauna from the 2005 King Kong remake have flared up. Indeed, a sum of traits justifies the comparison, at least partially so. The first one is a certain resemblance in pose and colors with the Nanmu “Berserker Rex” (actually, an unlicensed Indominus model). The second one is that, despite being remarkably complete, during fossilization the skull of “Sinraptor” hepingensis underwent some compression that distorted it. This is noted explicitly in Gao’s description, but – due to the general disinterest in this animal – most of the following restorations assumed the shape of the skull was genuine. It was only last year that Dan Folkes made an attempt to correct the distortion, resulting in a more normal-looking skull. The dentition, instead – that bizarre alternation of long and short teeth along the jaw – it’s an artifact of tooth replacement, which is photographed in death in a not really favorable instant from an aesthetic point of view. If only PNSO had given lips to the model (like in the companion artwork), this would’ve been far less noticeable – also because the animal’s teeth are quite small – and even more so if they had used an undeformed skull: let’s add to these factors the grey color and the result is not far from a movie monster. That’s a pity, because – these oddities aside – the skull shows the usual PNSO care, with the keratin of the nasal ridges (inferred from the roughness it left on the bones) highlighted with glossy paint. The skin is covered with fine scalation, which becomes larger at the orbital bones and along the curve of the jaw. The presence of large scales similar to those hypothesized for the Tyrannosauridae on the jaws is a bit perplexing, given that the main study about Allosauroid oral tissues (Barker et al. 2017) would not suggest its presence, but PNSO probably chose so to pair with the absence of lips. Unfortunately, a rather unsightly seam runs along the lower jaw: at least it’s symmetrical, so you can pretend it to be a trait of the animal.
There are interesting details in the neck and the torso that point to the attention paid to this model: the folds of loose skin in the neck area, which follows its curvature, and the way the latissimus dorsi is highlighted by the coloring. MetriacanthosauriNaes have very particular proportions within Theropoda: despite being often represented as basically Allosaurus clones, they have – when compared with the North American theropod – a stockier body and longer hind limbs, faithfully represented in the PNSO “Sinraptor” hepingensis. Among the MetriacanthosauriDae (see above for the difference), Yangchuanosaurus has completely different proportions: for example, its back had 13 rather elongated vertebrae against the 14 short vertebrae of “S.” hepingensis. The model’s forelimbs avoid the still-too-widespread trend of humanizing the muscles and have a forearm that is properly flattened when seen from the front, compared with the lateral view. The forelimbs of “Sinraptor” hepingensis are actually unknown, but that of the PNSO model is a plausible version, probably based on Sinraptor dongi. The same can be said of the hindlimbs, which in the fossil are not preserved below the femur: however, PNSO’s sculptor put great skill in representing them, as you can see by the folds of skin at the left ankle, where the weight is shifted as the animal takes a step forward.
Let’s see now the third detail that was criticized in this model: the tail, defined by many as “ratlike”. “Sinraptor” hepingensis is one of the few Metriacanthosauridae preserving a good portion of the tail (35 vertebrae): of these, the first five verts are taller than they are long, but it’s the opposite for the subsequent ones. So is the PNSO model correct? More or less. Gao notes that the chevrons (those “blades” on the underside of the caudal vertebrae – actually bony arches that protect the blood vessels to and from the tail and provide anchorage to the caudofemoral muscle) are rather poorly preserved. In fact, we in the western countries had a rather vague idea of how Metriacanthosauridae chevrons were shaped until some images from Dong et al. (1983), where you can see a chevron of Yangchuanosaurus, surfaced: unfortunately, Chinese publications from the last century have a long history of being hard to find and often untranslated. This chevron brings the tail of “Sinraptor” hepingensis back to more normal proportions, and it’s curious how something like this is represented in the artwork that accompanies the model. The musculature of the tail is well sculpted, with the caudofemoral swelling it from the base (although it could have been thicker).
The skin is covered with small scales – and in the Allosauroidea they were quite fine indeed (Hendrickx et al. 2022), even smaller than those we see in the model. In some places, such as the already mentioned margin of the orbit, the maxilla, and the shoulder, they become larger. On the sides, these small scales are interspersed with larger bumps, similar to those found in Carnotaurus, which are also highlighted by touches of darker paint: there is no evidence of their presence in “Sinraptor” hepingensis, but in addition to Carnotaurus other theropods (for example Albertosaurus, in the ventral area) presented them. The crest of spines that runs from the nape of the neck to the tip of the tail is instead totally speculative. Compared to other recent PNSO offers, the coloring is quite simple (reminiscent of that of Tarbosaurus), but it compensates for being well applied; there’s a return of the light wash of the first PNSOs, which highlight the details.
With its peculiar anatomy, “Sinraptor” hepingensis is an interesting addition to the PNSO’s Chinese dinosaurs, as well as an opportunity to learn more about this too often ignored group of theropods.
BIBLIOGRAPHY
Barker C.T.; Naish D.; Newham E.; Katsamenis O.L.; Dyke G. (2017) Complex neuroanatomy in the rostrum of the Isle of Wight theropod Neovenator salerii. Scientific Reports. 7 (1): 3749
Carrano M.T.; Benson R.B.J.; Sampson S.D. (2012) The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology. 10 (2): 211–300
Currie P.J.; Zhao X.J. (1994) A new carnosaur (Dinosauria, Theropoda) from the Jurassic of Xinjiang, People’s Republic of China. Canadian Journal of Earth Sciences. 30(10), 2037-2081
Dong Z.; Zhou S.; Zhang Y. (1983). Dinosaurs from the Jurassic of Sichuan. Palaeontologica Sinica, New Series C 162(23): 1-136
Gao Y. (1992) Yangchuanosaurus hepingensis – a new species of carnosaur from Zigong, Sichuan. Vertebrata PalAsiatica. 30 (4): 313–324
Hendrickx C.: Bell P.R.; Pittman M.; Milner A.R.C.; Cuesta E.; O’Connor J.; Loewen M.; Currie P.J.; Mateus O.; Kaye T.G.; Delcourt R. (2022) Morphology and distribution of scales, dermal ossifications, and other non‐feather integumentary structures in non‐avialan theropod dinosaurs. Biological Reviews, 10.1111/brv.12829, 97, 3, (960-1004)
The author thanks the users of the Discord server Theropoda/2 for their help in writing this review.