Open Paleo

Euoplocephalus

Lambe, 1910 yoo-OP-loh-SEF-uh-luhs /juːˌɒploʊˈsɛfələs/

From Greek 'eu' meaning 'well', 'hoplon' meaning 'weapon' or 'armor', and 'kephale' meaning 'head', meaning 'well-armored head'.

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

Euoplocephalus is a genus of large herbivorous ankylosaurid dinosaurs, living during the Late Cretaceous of Canada. It has only one named species, Euoplocephalus tutus.

Diagnosis

  1. Cranial ornamentation absent posterior to the orbits; lacks postocular caputegulae (subcircular ornamentation) at the bases of the squamosal and quadratojugal horns
  2. First cervical half ring with oval to subcircular-based keeled medial and lateral primary osteoderms, lacking interstitial osteoderms at their bases
  3. Tail club knob with semicircular major osteoderms in dorsal view
  4. Laterally directed sacral ribs
  5. Proportionately short postacetabular process of the ilium
  6. Anteriorly directed nares and no continuous keel between the squamosal horn and the supraorbitals

Species

Euoplocephalus tutus (Lambe, 1902)

Type species

First named as Stereocephalus tutus

From Latin 'tutus' meaning 'safely protected', referring to the extensive bony armor covering the animal's body.

Holotype
CMN 210 , Canadian Museum of Nature
Material
Fragmentary skull roof and partial first cervical half ring.
Horizon
Dinosaur Park Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
CMN locality P-189704, east side of the mouth of Berry Creek, Alberta, Canada

Synonyms of the genus

Name Type Reason
Stereocephalus preoccupied Name preoccupied by Stereocephalus (Insecta).

Notable specimens

  • AMNH 5403

    American Museum of Natural History largest individual

    Bears the largest known skull of Euoplocephalus, 411 millimeters long and 478 millimeters wide.

    Vickaryous & Russell (2002)

  • ROM 1930

    Royal Ontario Museum complementary

    The most informative specimen for armor configuration of the certain Euoplocephalus material, preserving some torso osteoderms in their original position, including osteoderms with a base length of fifteen centimeters.

    Arbour & Currie (2013)

References

  1. Lambe, L. M. (1910). Note on the parietal crest of Centrosaurus apertus and a proposed new generic name for Stereocephalus tutus. The Ottawa Naturalist 24: 149-151. lambe1910a
  2. Lambe, L. M. (1902). New genera and species from the Belly River Series (mid-Cretaceous). Geological Survey of Canada Contributions to Canadian Palaeontology 3(2): 25-81. doi:10.5281/zenodo.3233762

    Original description of the holotype (CMN 210) as Stereocephalus tutus; states no explicit diagnostic characters.

    lambe1902a
  3. Arbour, V. M.; Currie, P. J. (2013). Euoplocephalus tutus and the diversity of ankylosaurid dinosaurs in the Late Cretaceous of Alberta, Canada, and Montana, USA. PLOS ONE 8(5): e62421. doi:10.1371/journal.pone.0062421

    Redescribes E. tutus, restricts the taxon, and provides the revised differential diagnosis it carries.

    arbour2013a
  4. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the appearance features.

    paul2024a
  5. Vickaryous, M. K.; Russell, A. P. (2002). A redescription of the skull of Euoplocephalus tutus (Archosauria: Ornithischia): a foundation for comparative and systematic studies of ankylosaurian dinosaurs. Zoological Journal of the Linnean Society 137(1): 157-186. doi:10.1046/j.1096-3642.2003.00045.x

    Gives the holotype's horizon as the Dinosaur Park Formation, formerly the Oldman, and records that no coordinate was ever taken.

    vickaryous2002a