Albertaceratops

Albertaceratops; Temporal range: Late Cretaceous, 77.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Skull in Philip J. Currie Dinosaur Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Order:	†Ornithischia
Suborder:	†Ceratopsia
Family:	†Ceratopsidae
Subfamily:	†Centrosaurinae
Genus:	†Albertaceratops; Ryan, 2007
Species:	†A. nesmoi
Binomial name
	†Albertaceratops nesmoi; Ryan, 2007

Albertaceratops (meaning "Alberta horned face") was a genus of centrosaurine horned dinosaur from the middle Campanian-age Upper Cretaceous Oldman Formation of Alberta, Canada.^[1]

Description[]

Restoration

Albertaceratops is unusual in combining long brow horns with an otherwise centrosaurine skull, as centrosaurines normally possess short brow horns. Over its nose was a bony ridge, and on its frill were two large outwardly-projecting hooks.^[1] Its size has been estimated at 5.8 metres (19 ft) and 3,500 kilograms (7,700 lb).^[2]

Discovery and naming[]

Skull of the Albertaceratops nesmoi holotype, TMP 2001.26.1

Albertaceratops is known from a single complete skull (TMP.2001.26.1) found in August 2001 and skull and postcranial fragments. A phylogenetic analysis carried out by its describer, Michael J. Ryan, found it to be the most basal centrosaurine.^[1] Additional specimens were reported from a bonebed in the Judith River Formation of Montana, which is equivalent to the Oldman Formation and differentiated only by the Canada–US border. However, further study showed these remains to come from a different centrosaurine, Medusaceratops. Both ceratopsids lived during the same time period, about 77.5 million years ago.^[3]

The specific name, A. nesmoi, is derived from the name of Cecil Nesmo, a rancher living in Manyberries, Alberta, a town of less than 100 people located 71 km south of Medicine Hat. The rancher was thus honored in recognition of his efforts to aid fossil hunters.^[1]

Classification[]

Coronosaurus and Albertaceratops in environment

Size of Albertaceratops compared to a human

The cladogram presented below follows a phylogenetic analysis by Chiba et al. (2017), which included a systematic re-evaluation of Medusaceratops lokii:^[4]

Centrosaurinae

	Diabloceratops eatoni

	Machairoceratops cronusi

Nasutoceratopsini

	Avaceratops lammersi (ANSP 15800)

	MOR 692

	CMN 8804

	Nasutoceratops titusi

	Malta new taxon

Xenoceratops foremostensis

	Sinoceratops zhuchengensis

	Wendiceratops pinhornensis

Albertaceratops nesmoi

Medusaceratops lokii

Eucentrosaura

Centrosaurini

	Rubeosaurus ovatus

	Styracosaurus albertensis

Coronosaurus brinkmani

	Centrosaurus apertus

	Spinops sternbergorum

Pachyrhinosaurini

Einiosaurus procurvicornis

Pachyrostra

Achelousaurus horneri

Pachyrhinosaurus canadensis

	Pachyrhinosaurus lakustai

	Pachyrhinosaurus perotorum

References[]

^ ^a ^b ^c ^d Ryan, Michael J. (2007). "A New Basal Centrosaurine Ceratopsid from the Oldman Formation, Southeastern Alberta". Journal of Paleontology. 81 (2): 376–396. doi:10.1666/0022-3360(2007)81[376:ANBCCF]2.0.CO;2. ISSN 0022-3360.
^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 259
^ Ryan, Michael J.; Russell, Anthony P., and Hartman, Scott. (2010). "A New Chasmosaurine Ceratopsid from the Judith River Formation, Montana", In: Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth (eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Indiana University Press, 656 pp. ISBN 0-253-35358-0.
^ Kentaro Chiba; Michael J. Ryan; Federico Fanti; Mark A. Loewen; David C. Evans (2018). "New material and systematic re-evaluation of Medusaceratops lokii (Dinosauria, Ceratopsidae) from the Judith River Formation (Campanian, Montana)". Journal of Paleontology. in press (2): 272–288. doi:10.1017/jpa.2017.62. S2CID 134031275.