# Shamosaurus

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Extinct genus of reptiles

Shamosaurus Temporal range: Early Cretaceous, Aptian–Albian PreꞒ Ꞓ O S D C P T J K Pg N Scientific classification Kingdom: Animalia Phylum: Chordata Class: Reptilia Clade: Dinosauria Clade: †Ornithischia Clade: †Thyreophora Clade: †Ankylosauria Family: †Ankylosauridae Subfamily: †Shamosaurinae Tumanova, 1983 Genus: †Shamosaurus Tumanova, 1983 Species: †S. scutatus Binomial name †Shamosaurus scutatus Tumanova, 1983

***Shamosaurus*** is an [extinct](/source/Extinct) [genus](/source/Genus) of herbivorous basal [ankylosaurid](/source/Ankylosaurid) [ankylosaur](/source/Ankylosaur) from [Early Cretaceous](/source/Early_Cretaceous) ([Aptian](/source/Aptian) to [Albian](/source/Albian) stage) deposits of [Höövör](https://en.wikipedia.org/w/index.php?title=H%C3%B6%C3%B6v%C3%B6r&action=edit&redlink=1), [Mongolia](/source/Mongolia).

## Discovery and naming

In 1977, a Soviet-Mongolian expedition discovered the skeleton of an unknown ankylosaurian at the Hamrin-Us site in [Dornogovi Province](/source/Dornogovi_Province). This was the first discovery of an ankylosaur in the [Lower Cretaceous](/source/Lower_Cretaceous) of Mongolia.[1]

In [1983](/source/1983_in_paleontology), [Tatyana Tumanova](https://en.wikipedia.org/w/index.php?title=Tatyana_Tumanova&action=edit&redlink=1) named and described the [type species](/source/Type_species) *Shamosaurus scutatus*. The generic name is derived from [Mandarin](/source/Mandarin_Chinese) *sha mo*, "sand desert", the Chinese name for the [Gobi](/source/Gobi). The [specific name](/source/Specific_name_(zoology)) means "protected by a shield" in [Latin](/source/Latin), a reference to the body armour.[1]

*Shamosaurus* is known from the [holotype](/source/Holotype) **PIN N 3779/2**, collected from the [Dzunbain Formation](/source/Dzunbain_Formation), equivalent to the [Khukhtekskaya Formation](/source/H%C3%BChteeg_Svita) and dating from the [Aptian](/source/Aptian)-[Albian](/source/Albian), about 115 million years old. It consists of a complete [skull](/source/Skull), lower [jaws](/source/Jaw) and partial postcranial skeleton with armor. Only the skull was described in 1983.[1] Later the specimens PIN 3779/1, a skull piece, and PIN 3101, a lower jaw, were referred. The fossils are part of the collection of the Palaeontological Institute at [Moscow](/source/Moscow). The holotype skull is exhibited there, together with two cervical halfrings.[2]

## Description

*Shamosaurus* was a medium-sized ankylosaurian. In 2010, [Gregory S. Paul](/source/Gregory_S._Paul) estimated its body length at 5 metres (16 ft), its weight at 2 tonnes (2.2 short tons).[3] In 2012 [Holtz](/source/Thomas_R._Holtz_Jr.) gave a higher estimation of 7 meters (23 ft).[4]

In 2014, [Victoria Arbour](/source/Victoria_Arbour) gave a revised list of distinguishing traits. The [osteoderms](/source/Osteoderms) on the skull roof are not very pronounced nor separated as distinctive *caputegulae*, head tiles. The squamosal horns on the rear skull corners are short and slightly rounded. The quadratojugal horn on the cheek has its apex in the middle. The rear rim of the skull roof has no clear (nuchal) processes.[2]

*Shamosaurus scutatus* shares many [cranial](/source/Skull) similarities with *[Gobisaurus](/source/Gobisaurus) domoculus*, including a rounded [squamosal](/source/Squamosal), large elliptical [orbital fenestrae](/source/Orbital_fenestrae) (oval eye sockets) and oval external [nares](/source/Nares) (nostrils), a [deltoid](/source/Kite_(geometry)) [dorsal](/source/Dorsum_(biology)) profile with a narrow [rostrum](/source/Rostrum_(anatomy)) (the snout is tongue-shaped and narrow in top view), quadratojugal protuberances (cheek horns), and caudolaterally directed paroccipital processes (extensions of the rear skull obliquely pointing to behind and sideways). But the two [taxa](/source/Taxa) may be distinguished by differences in the length of the maxillary tooth row (40% instead of 26,7% of total skull length), an unfused basipterygoid-pterygoid process in *Gobisaurus*, the presence of an elongate vomerine premaxillary process in *Gobisaurus*, and the presence of cranial sculpting in *Shamosaurus*, but not in *Gobisaurus*.[5] The last difference was denied by Arbour who concluded that the degree of sculpting was roughly the same.[2]

*Shamosaurus* had a rather flat skull. The upper beak was sharp and obliquely appending to the front. The beak lacked any teeth. The jaw joint was located far behind the level of the eye socket. The [occipital condyle](/source/Occipital_condyle), and with it the entire head, was obliquely directed to below. A secondary palate was present.[1]

The armour of *Shamosaurus* contained two cervical halfrings with six segments each, protecting the neck. Also keeled [osteoderms](/source/Osteoderm) and flat oval scutes were present.[1]

## Phylogeny

Tumanova placed *Shamosaurus* in the [Ankylosauridae](/source/Ankylosauridae).[1] She also named a [Shamosaurinae](/source/Shamosaurinae), a group of basal ankylosaurids. In 2014, Arbour recovered an evolutionary tree in which *Shamosaurus* was the [sister species](/source/Sister_species) of *Gobisaurus*.[2]

*Shamosaurus* in a [cladogram](/source/Cladogram) simplified from Zheng *et al*. (2018):[6]

Ankylosauridae Kunbarrasaurus Hylaeosaurus Liaoningosaurus Chuanqilong Cedarpelta Shamosaurus Gobisaurus Ankylosaurinae Jinyunpelta Crichtonpelta Pinacosaurus spp. Saichania Zaraapelta Tarchia Ankylosaurini Tsagantegia Talarurus Nodocephalosaurus Ziapelta Euoplocephalus Ankylosaurus Anodontosaurus Scolosaurus Zuul Dyoplosaurus

In phylogenetic analyses by Xing *et al*. (2024), *Shamosaurus* is recovered as a member of Shamosaurinae or as an ankylosaurid, more derived than *Gobisaurus*. Below are two simplified cladograms from that study:[7]

Topology A: Zheng et al. (2018) dataset + Datai (14-taxon deletion) Ankylosauridae Cedarpelta Chuanqilong Liaoningosaurus Shamosaurinae Gobisaurus Shamosaurus Ankylosaurinae Topology B: Raven et al. (2023) dataset + Datai (34-taxon deletion) Ankylosauridae Jinyunpelta Gobisaurus Chuanqilong Shamosaurus Ankylosaurinae

## See also

- [Dinosaurs portal](https://en.wikipedia.org/wiki/Portal:Dinosaurs)

- [Timeline of ankylosaur research](/source/Timeline_of_ankylosaur_research)

## Notes

1. ^ [***a***](#cite_ref-Tumanova1983_1-0) [***b***](#cite_ref-Tumanova1983_1-1) [***c***](#cite_ref-Tumanova1983_1-2) [***d***](#cite_ref-Tumanova1983_1-3) [***e***](#cite_ref-Tumanova1983_1-4) [***f***](#cite_ref-Tumanova1983_1-5) T.A. Tumanova, 1983, "Pervyy ankilozavr iz nizhnego mela Mongolii", In: L.P. Tatarinov, R. Barsbold, E. Vorobyeva, B. Luvsandanzan, B.A. Trofimov, Yu. A. Reshetov, & M.A. Shishkin (eds.), *Iskopayemyye reptilii mongolii*. Trudy Sovmestnaya Sovetsko-Mongol'skaya Paleontologicheskaya Ekspeditsiya **24**: 110-118

1. ^ [***a***](#cite_ref-Arbour2014_2-0) [***b***](#cite_ref-Arbour2014_2-1) [***c***](#cite_ref-Arbour2014_2-2) [***d***](#cite_ref-Arbour2014_2-3) Arbour, Victoria Megan, 2014. *Systematics, evolution, and biogeography of the ankylosaurid dinosaurs*. Ph.D thesis, University of Alberta

1. **[^](#cite_ref-3)** Paul, G.S., 2010, *The Princeton Field Guide to Dinosaurs*, Princeton University Press p. 230

1. **[^](#cite_ref-4)** Holtz Jr., Tomas R. (2012). ["Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages"](http://www.geol.umd.edu/~tholtz/dinoappendix/HoltzappendixWinter2011.pdf) (PDF).

1. **[^](#cite_ref-Vickaryous2004_5-0)** Vickaryous M.K., [Maryańska T.](/source/Teresa_Marya%C5%84ska), Weishampel D.B., 2004, "Ankylosauria". Chapter 17 in: Weishampel D.B., Dodson P., Osmólska H., editors. *The Dinosauria*. 2nd ed. Berkeley (CA): University of California Press. p. 363–392

1. **[^](#cite_ref-Jinyunpelta_6-0)** Wenjie Zheng; Xingsheng Jin; Yoichi Azuma; Qiongying Wang; Kazunori Miyata; Xing Xu (2018). ["The most basal ankylosaurine dinosaur from the Albian–Cenomanian of China, with implications for the evolution of the tail club"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5829254). *Scientific Reports*. **8** (1) 3711. [Bibcode](/source/Bibcode_(identifier)):[2018NatSR...8.3711Z](https://ui.adsabs.harvard.edu/abs/2018NatSR...8.3711Z). [doi](/source/Doi_(identifier)):[10.1038/s41598-018-21924-7](https://doi.org/10.1038%2Fs41598-018-21924-7). [PMC](/source/PMC_(identifier)) [5829254](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5829254). [PMID](/source/PMID_(identifier)) [29487376](https://pubmed.ncbi.nlm.nih.gov/29487376).

1. **[^](#cite_ref-Datai_7-0)** Xing, Lida; Niu, Kecheng; Mallon, Jordan; Miyashita, Tetsuto (2023). ["A new armored dinosaur with double cheek horns from the early Late Cretaceous of southeastern China"](https://www.researchgate.net/publication/378305788). *Vertebrate Anatomy Morphology Palaeontology*. **11**. [doi](/source/Doi_(identifier)):[10.18435/vamp29396](https://doi.org/10.18435%2Fvamp29396). [ISSN](/source/ISSN_(identifier)) [2292-1389](https://search.worldcat.org/issn/2292-1389).

## References

- Matthew K. Vickaryous, Anthony P. Russell, Philip J. Currie, and Xi-Jin Zhao. 2001. A new ankylosaurid (Dinosauria: Ankylosauria) from the Lower Cretaceous of China, with comments on ankylosaurian relationships. Canadian Journal of Earth Sciences/Rev. can. sci. Terre 38(12):1767-1780.

## External links

- [*Shamosaurus* in the Dino Directory](http://www.nhm.ac.uk/jdsml/nature-online/dino-directory/detail.dsml?Genus=Shamosaurus)

v t e Ankylosauria Kingdom: Animalia Phylum: Chordata Clade: Dinosauria Clade: Ornithischia Clade: Thyreophora Avemetatarsalia see Avemetatarsalia Ornithischia see Ornithischia Ankylosauria see below↓ Ankylosauria Ankylosauria Cryptosaurus Dracopelta Priodontognathus Sarcolestes Serendipaceratops? Spicomellus Stegosaurides? Tianchisaurus Vectipelta Parankylosauria? Antarctopelta Kunbarrasaurus Minmi Patagopelta Stegouros Euankylosauria Nodosauridae Acanthopholis Anoplosaurus Dongyangopelta Gargoyleosaurus? Gastonia? Glyptodontopelta Horshamosaurus Hylaeosaurus? Invictarx Mymoorapelta? Polacanthoides? Priconodon? Propanoplosaurus Rhadinosaurus Sauroplites Polacanthinae Gargoyleosaurus? Gastonia? Hoplitosaurus Peloroplites? Polacanthus Taohelong? Nodosaurinae Acantholipan Ahshislepelta? Borealopelta Niobrarasaurus Nodosaurus Peloroplites? Sauropelta Silvisaurus Tatankacephalus Panoplosaurini Animantarx Denversaurus Edmontonia Panoplosaurus Texasetes Struthiosaurini Europelta Hungarosaurus Pawpawsaurus Stegopelta Struthiosaurus Ankylosauridae Ahshislepelta? Aletopelta? Cedarpelta Chuanqilong Huaxiazhoulong Hylaeosaurus? Liaoningosaurus Zhejiangosaurus Shamosaurinae Gobisaurus Shamosaurus Zhongyuansaurus? Ankylosaurinae Bissektipelta Crichtonpelta Crichtonsaurus Datai Eopinacosaurus Jinyunpelta Minotaurasaurus Pinacosaurus Saichania Shanxia? Tarchia Tianzhenosaurus? Tsagantegia Zaraapelta Ankylosaurini Akainacephalus Ankylosaurus Anodontosaurus Dyoplosaurus Euoplocephalus Nodocephalosaurus Oohkotokia Platypelta Scolosaurus Talarurus Ziapelta Zuul See also: Timeline Category

Taxon identifiers Shamosaurus Wikidata: Q139221 Wikispecies: Shamosaurus EoL: 4530875 GBIF: 4823329 IRMNG: 1434556 Open Tree of Life: 4946564 Paleobiology Database: 52794

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Adapted from the Wikipedia article [Shamosaurus](https://en.wikipedia.org/wiki/Shamosaurus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Shamosaurus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.