Open Paleo

Minotaurasaurus

Miles & Miles, 2009 min-uh-TOR-a-SOR-us Disputed

Named after the Minotaur of Greek mythology (the bull of Minos) combined with Greek 'sauros' (lizard); meaning 'Minos's bull reptile'.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Minotaurasaurus is a monospecific genus of ankylosaurid dinosaur that lived in Mongolia during the Late Cretaceous (late Campanian stage, ~75-71 Ma) in what is now the Djadokhta Formation. The type and only species, Minotaurasaurus ramachandrani, is known from two skulls, a cervical vertebra and a cervical half ring. It was named and described in 2009 by Clifford Miles and Clark Miles. The holotype was bought at the Tucson Gem and Mineral Show and has been described as illegally acquired; where it was found was never recorded, and its matrix points to the Gobi Desert of Mongolia or China. Arbour and colleagues (2014) and Arbour and Currie (2015) sank it into Tarchia kielanae; Penkalski and Tumanova (2017) and Penkalski (2026) argue that it is a distinct genus.

Under dispute

The validity of Minotaurasaurus is contested. Arbour and colleagues (2014) sank it into Tarchia kielanae, and Arbour and Currie (2015) kept the synonymy. Penkalski and Tumanova (2017) argued that it is a distinct genus; Wiersma and Irmis (2018) followed them in coding it separately, and Penkalski (2026) recovered it as the sister taxon of Pinacosaurus. Retained as a valid ankylosaurine pending consensus.

Diagnosis

  1. Skull with large, horizontally elliptical external nares rimmed by well-developed osteoderm
  2. Premaxillary part of snout broad with foramina for premaxillary and maxillary sinuses housed within external nares
  3. Occipital condyle poorly developed, directed ventrally
  4. Quadrate nearly vertical with distal articular condyle at level between posterior rim of skull and orbit
  5. Skull roof not overhanging occiput
  6. Maxillary shelf well-developed and wide below middle of orbit
  7. Pterygoid body almost horizontal, not vertical
  8. Narial osteoderms large and highly ornamented creating flared, bull-like appearance

Species

Minotaurasaurus ramachandrani Miles & Miles, 2009 Disputed

Type species

Named for Vilayanur S. Ramachandran, the neuroscientist who purchased the type skull at a fossil show in Tucson, Arizona in 2003.

Holotype
INBR21004 , Victor Valley Museum
Material
A skull with complete lower jaws and predentary.
Horizon
Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Ömnögovi, Mongolia Where the holotype came from was never recorded, since it was purchased rather than collected. Penkalski and Tumanova (2017) assign the Djadokhta Formation on the evidence of a referred specimen, while Arbour and colleagues (2014) argue for the Baruungoyot in sinking the genus into Tarchia. The unit turns on which taxonomy is accepted.

Notable specimens

  • MAE 98 179

    Mongolian American Museum Expedition, Mongolian Academy of Sciences complementary

    Skull, axis and first cervical half-ring from Ukhaa Tolgod, Djadokhta Formation, referred to Minotaurasaurus by Alicea and Loewen (2013) and Penkalski and Tumanova (2017): the only specimen of the genus with a known horizon, cited as evidence that it is distinct from Tarchia.

    Alicea & Loewen (2013)Penkalski & Tumanova (2017)

References

  1. Miles, C. A.; Miles, C. J. (2009). Skull of Minotaurasaurus ramachandrani, a new Cretaceous ankylosaur from the Gobi Desert. Current Science 96(1): 65-70. miles2009a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the appearance features.

    paul2024a
  3. Penkalski, P.; Tumanova, T. (2017). The cranial morphology and taxonomic status of Tarchia (Dinosauria: Ankylosauridae) from the Upper Cretaceous of Mongolia. Cretaceous Research 70: 117-127. Elsevier BV. doi:10.1016/j.cretres.2016.10.004

    Argues that the holotype of Minotaurasaurus is not referable to Tarchia kielanae, so the genus is valid; gives a revised diagnosis and refers MAE 98 179 from Ukhaa Tolgod to it.

    penkalski2017a
  4. Wiersma, J. P.; Irmis, R. B. (2018). A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. et sp. nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA. PeerJ 6: e5016. PeerJ. doi:10.7717/peerj.5016

    Treated Minotaurasaurus as distinct from Tarchia kielanae, following Penkalski and Tumanova (2017), and coded it as a separate taxon.

    wiersma2018a
  5. Arbour, V. M.; Currie, P. J.; Badamgarav, D. (2014). The ankylosaurid dinosaurs of the Upper Cretaceous Baruungoyot and Nemegt formations of Mongolia. Zoological Journal of the Linnean Society 172(3): 631-652. Oxford University Press (OUP). doi:10.1111/zoj.12185

    Treated Minotaurasaurus as a junior synonym of Tarchia kielanae.

    arbour2014b
  6. Arbour, V. M.; Currie, P. J. (2015). Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs. Journal of Systematic Palaeontology 14(5): 385-444. Informa UK Limited. doi:10.1080/14772019.2015.1059985

    Keeps Minotaurasaurus ramachandrani as a junior synonym of Tarchia kielanae.

    arbour2015a
  7. Penkalski, P. (2026). The morphology and systematics of Pinacosaurus. Historical Biology 1-42. doi:10.1080/08912963.2026.2633178

    Treats Minotaurasaurus as distinct from Tarchia and recovers it as the sister taxon of Pinacosaurus.

    penkalski2026a
  8. Alicea, J.; Loewen, M. (2013). New Minotaurasaurus material from the Djodokta Formation establishes new taxonomic and stratigraphic criteria for the taxon. Journal of Vertebrate Paleontology, Program and Abstracts 76.

    Refers a second specimen from Ukhaa Tolgod, Djadokhta Formation, to Minotaurasaurus; calls the holotype illegally acquired.

    alicea2013a