Edmontonia
Named after the Edmonton Formation (now the Horseshoe Canyon Formation) in Alberta, Canada, where it was first found; Edmonton itself is named after Edmonton in London, England
Edmontonia is a genus of panoplosaurin nodosaurid dinosaur from the Late Cretaceous Period of what is now western North America. It is named after the Edmonton Formation (now the Horseshoe Canyon Formation in Canada), the unit of rocks where it was first found.
Diagnosis
- Skull nearly twice as long as broad (roughly oblong), highly elongated relative to other Upper Cretaceous ankylosaurs
- Lateral temporal fossa in normal lateral position facing outward, not covered by dermal bone as in Panoplosaurus
- Teeth large and numerous: 16 alveoli in maxilla (135 mm) and 18 in dentary (155 mm), larger than in other known ankylosaurs except Palaeoscincus
- Palatines and pterygoids united on midline forming a sharp-edged longitudinal ridge that divides the mouth cavity, extending below the level of the maxillary teeth
- Dermal plates on skull defined by shallow sulci (not deep circumscribing grooves), with a large oval central cranial plate longer than broad
Species
Edmontonia longiceps Sternberg, 1928
Type species
From Latin 'longus' meaning 'long' and 'caput' (genitive 'capitis', contracted as '-ceps') meaning 'head', referring to the elongated skull of the type specimen.
- Holotype
- NMC 8531 , Canadian Museum of Nature
- Material
- Skull and right mandibular ramus, most dorsal vertebrae and ribs, sacrum and pelvic arch, nine caudal vertebrae, one fore limb, most of one hind limb, and numerous dermal scutes
- Horizon
- Horseshoe Canyon Formation, Campanian–Maastrichtian, Late Cretaceous , 83.6–66.0 million years ago
- Locality
- Sec. 28, T. 31, R. 21 W4, 7 miles northwest of Morrin, Alberta, Canada
Synonyms of the genus
| Name | Type | Reason |
|---|---|---|
| Chassternbergia | junior subjective | Erected by Bakker (1988) as a subgenus of Edmontonia; later workers rejected that split, and Vickaryous and colleagues (2004) list Chassternbergia among the synonyms of Edmontonia. |
References
- Sternberg, C. M. (1928). A new armored dinosaur from the Edmonton Formation of Alberta. Transactions of the Royal Society of Canada, series 3 22: 93-106. sternberg1928a
-
Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.
Source of the mass estimate.
paul2024a -
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Source of the hip height estimate, and the appearance features.
jones2026a -
Olshevsky, G. (1991). A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2: 1-196.
Raised Edmontonia rugosidens to full genus, rarely followed since.
olshevsky1991a -
Bakker, R. T. (1988). Review of the Late Cretaceous nodosauroid Dinosauria: Denversaurus schlessmani, a new armor-plated dinosaur from the Latest Cretaceous of South Dakota, the last survivor of the nodosaurians, with comments on Stegosaur-Nodosaur relationships. Hunteria 1(3): 1-23.
Reviewed Late Cretaceous nodosaurids, erecting Denversaurus for Edmontonia-grade material.
bakker1988a -
Livius, M. C. H.; Witmer, L. M.; Ryan, M. J.; Maddin, H. C.; Mallon, J. C. (2026). Redescription of the Panoplosaurus mirus (Ankylosauria: Nodosauridae) holotype skull using computed tomography, and a new comparative scheme for panoplosaurin cranial ornamentation. Journal of Vertebrate Paleontology. doi:10.1080/02724634.2026.2636589
Gives the holotype's provenance as 11 km northwest of Morrin, distinct from the South Dakota specimen later referred to this species.
livius2026a - Vickaryous, M. K.; Maryańska, T.; Weishampel, D. B. (2004). Ankylosauria. The Dinosauria, Second Edition (Weishampel, D. B.; Dodson, P.; Osmólska, H., eds.) 363-392. University of California Press, Berkeley. vickaryous2004a