Wuerhosaurus was a stegosaur dinosaur which lived in China during the early and middle Cretaceous Period. It was one of the last stegosaurs to have existed, as they had largely been replaced elsewhere in the world by the ankylosaurians by that time.
Wuerhosaurus is known from two partial skeletons belonging to two different species of that genus. Based upon their size, the animal is estimated to have reached somewhere between 15 to 25 feet long, making it almost as big or perhaps just as big as Stegosaurus. However, unlike Stegosaurus with its tall diamond-shaped plates, Wuerhosaurus‘ plates were short and stumpy.
There are two species of Wuerhsaurus which are currently recognized by science: W. homheni (1973) and W. ordosensis (1993). The fossils of Wuerhosaurus homheni were found in 1964 near Wuerho, Xinjiang Province, China within the rocks of the Lianmuqin Formation (Dong 1973, pages 45-52; Xing et al 2020, page 76). The dating of this formation is controversial, as paleontologists don’t seem to be able to agree on a date range (Chen et al 1991, page 4,068; Maisch et al 2004, page 625; Brusatte et al 2010, page 282; Brusatte et al 2012, pages 65-66, 70; Yang et al 2008, pages 345-363; Xi et al 2019, pages 256-286). However, numerous popular media books from the 1990s and 2000s state that Wuerhosaurus lived 135-120 MYA.
The fossils of Wuerhosaurus ordosensis were found in 1988 within the Ordos Basis, which lies within the “Inner Mongolia Autonomous Region” in northern China. The rocks there are from the Ejinhoro Formation and date to the boundary between the Aptian and Albian Stages of the middle Cretaceous Period, about 113 million years ago. The animal was named in 1993. Wuerhosaurus ordosensis is believed to have been slightly smaller compared to W. homheni (Dong 1993, pages 2,174-2,176).
A third species of Wuerhosaurus was named in 2014, called Wuerhosaurus mongoliensis (Ulansky 2014, pages 1-35). However, on further examination, it was determined that it was an entirely new genus, and so it was renamed Mongolostegus exspectabilis in 2018 (Tumanova and Alifanov 2018, pages 1,771-1,779).
Although two partial skeletons have been found, there is still a lot that we don’t know about Wuerhosaurus‘ appearance. No skull was found with either specimen, and we don’t know how many back plates or tail spikes it would have had. Phylogeny suggests that it was an advanced stegosaur closely related to Stegosaurus itself, so it probably had a very similar appearance. This means that it likely had four tail spikes, no shoulder spikes as is seen in creatures like Kentrosaurus and Lexovisaurus, and it might have had pebbly dermal armor protecting the underside of its throat. One can only hope that more skeletons are found in the future.
In 2008, Susannah Maidment and her colleagues stated that Wuerhosaurus and Stegosaurus were so closely related that Wuerhosaurus should really be re-classified as a Chinese species of Stegosaurus. However, nobody seems to have taken any notice of that and practically everybody still refers to it as Wuerhosaurus (Maidment et al 2008, pages 368, 379-380, 384).
There has also been a certain degree of talk concerning Wuerhosaurus‘ back plates. A total of three dorsal plates are known from Wuerhosaurus: two from W. homheni and one from W. ordosensis. The two plates from W. homheni are grouped together with the rest of the skeleton under the collection ID code “IVPP V4006”. The dorsal plate from W. ordosensis has been designated with the collection ID code “IVPP V6878” (Maidment et al 2008, pages 379-380, 384).
Susannah Maidment claimed that the short rectangular plates which Wuerhosaurus is depicted as having are actually a mistake. Her article claims that the plates were broken off horizontally, giving the illusion that they had a different shape, when in actuality they were probably very Stegosaurus-esque in their appearance (Comment #47, in Science Blogs. “Stegosaur Wars: the SJG stegosaur special, part I”). In 2010, the British paleontologist David Hone examined one of the two dorsal plates from “IVPP V4006”, and he also remarked that the dorsal edge of the plate looked broken rather than having a natural edge (“Not Wuerhosaurus homheni”). Yet, remember that three plates were found belonging to two skeletons, and I find it hard to believe that all three plates could be broken in the exact same way – that would be a truly remarkable coincidence. Not impossible, but indeed very unlikely.
Below is a drawing which I made of the species Wuerhosaurus homheni, made with No.2 and No.3 pencil. The drawing measures 12 inches long from nose to tail, not including the tail spikes, which would make the drawing 1/20 scale if the creature measured 20 feet long, as I suspect it did. NOTE: I wasn’t satisfied with the original drawing which was posted here in late July, so I replaced it with the drawing that you see below.
Wuerhosaurus homheni. © Jason R. Abdale (August 11, 2022).
Keep your pencils sharp, people.
Bibliography
Brusatte, Stephen L.; Benson, Roger B. J.; Xu, Xing (2010). “The evolution of large-bodied theropod dinosaurs during the Mesozoic in Asia”. Journal of Iberian Geology, volume 36, issue 2 (December 2010). Pages 275–296.
https://www.researchgate.net/publication/260714806_The_evolution_of_large-bodied_therood_dinosaurs_during_the_Mesozoic_in_Asia.
Brusatte, Stephen L.; Benson, Roger B. J.; Xu, Xing (2012). “A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous of China”. Acta Palaeontologica Polonica, volume 57, issue 1 (March 1, 2012). Pages 65-72.
https://bioone.org/journals/acta-palaeontologica-polonica/volume-57/issue-1/app.2010.0125/A-Reassessment-of-Kelmayisaurus-petrolicus-a-Large-Theropod-Dinosaur-from/10.4202/app.2010.0125.full.
Chen, Yan; Cogne, Jean-Pascal; Courtillot, Vincent; Avouac, Jean-Philippe; Tapponnier, Paul; Wang, Gongque; Bai, Meixiang; You, Hongzi; Li, Ming; Wei, Chunsheng; Buffetaut, Eric (1991). “Paleomagnetic Study of Mesozoic Continental Sediments Along the Northern Tien Shan (China) and Heterogeneous Strain in Central Asia”. Journal of Geophysical Research, volume 96, issue 83 (March 10, 1991). Pages 4,065-4,082.
https://authors.library.caltech.edu/34009/1/90JB02699.pdf.
Dong, Zhiming (1973). “Dinosaurs from Wuerho”. Memoirs of the Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica, volume 11 (1973). Pages 45-52.
Dong, Zhiming (1993). “A new species of stegosaur (Dinosauria) from the Ordos Basin, Inner Mongolia, People’s Republic of China”. Canadian Journal of Earth Sciences, volume 30, issue 10 (1993). Pages 2,174-2,176.
Maidment, Susannah C.R.; Norman, David B.; Barrett, Paul M.; Upchurch, Paul (2008). “Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia)”. Journal of Systematic Palaeontology, volume 6, issue 4 (November 24, 2008). Pages 367-407.
https://www.researchgate.net/publication/230854863_Systematics_and_phylogeny_of_Stegosauria_Dinosauria_Ornithischia.
Maisch, Michael W.; Matzke, Andreas T.; Sun, Ge (2004). “A new dsungaripteroid pterosaur from the Lower Cretaceous of the southern Junggar Basin, north-west China”. Cretaceous Research, volume 25, issue 5 (October 2004). Pages 625-634.
Tumanova, T. A.; Alifanov, V. R. (2018) “First Record of Stegosaur (Ornithischia, Dinosauria) from the Aptian-Albian of Mongolia”. Paleontological Journal, volume 52, issue 14 (2018). Pages 1,771-1,779.
Ulansky, Roman. E. (2014). “Evolution of the stegosaurs (Dinosauria; Ornithischia)”. Dinologia (2014). Pages 1-35.
http://dinoweb.narod.ru/Ulansky_2014_Stegosaurs_evolution.pdf.
Xi, Dangpeng; Wan, Xiaoqiao; Li, Guobiao; Li, Gang (2019). “Cretaceous integrative stratigraphy and timescale of China”. Science China Earth Sciences, volume 62, issue 1 (2019). Pages 256-286.
Xing, Lida; Lockley, Martin G.; Li, Zhongdong; Klein, Hendrik; Chen, Shaojie; Persons IV, W. Scott; Wang, Miaoyan (2020). “Large Scale Dinoturbation in Braided Stream Deposits: Evidence from the Cretaceous Tugulu Group of the Hami Area, Eastern Xinjiang, China”. Biosis: Biological Systems, volume 1, issue 2 (2020). Pages 72-84.
Yang, J. L.; Wang, Q. F.; Lu, H. N. (2008). “Cretaceous charophyte floras from the Jungar Basin, Xinjiang, China”. Acta Micropalaeontologica Sinica, volume 12, issue 25 (2008). Pages 345-363.
Archosaur Musings. “Not Wuerhosaurus homheni”, by David Hone (January 5, 2010). https://archosaurmusings.wordpress.com/2010/01/05/not-wuerhosaurus-homheni/. Accessed on July 29, 2022.
Science Blogs. “Stegosaur Wars: the SJG stegosaur special, part I”, by tetrapodzoology (December 29, 2010). https://scienceblogs.com/tetrapodzoology/2010/12/29/stegosaur-wars. Accessed on July 29, 2022.
Categories: Paleontology, Uncategorized
DINOSAURS AND BARBARIANS 
A most excellent post on Wuerhosaurus. It’s a classic example of “we need more fossils” to help settle the debate on the plates, but I think you make a fair point for why the unusual shape could be how they appeared.