Wapiti Formation

The Wapiti Formation is a geological formation of the Western Canada Sedimentary Basin in northwestern Alberta, and northeastern British Columbia, Canada. Its deposition spanned the time interval from the upper Campanian through to the lower Maastrichtian, between approximately 80 and 68 Ma.^[2][3] It was named by G.M. Dawson in 1881,^[1] presumably for exposures along the lower part of the Wapiti River and downstream along the Smoky River in Alberta.^[4]

Wapiti Formation
Stratigraphic range: Campanian–Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Lithology
Primary	Sandstone, siltstone, mudstone
Other	conglomerate, coal
Location
Region	Alberta
Country	Canada
Type section
Named for	Lower part of Wapiti River
Named by	G.M. Dawson, 1881.[1]

Dinosaur remains are among the fossils that have been recovered from the Cretaceous portion of the formation.^[5][6] The Wapiti Formation does not produce many fossils due to its limited surface exposure and accessibility, although two Pachyrhinosaurus bone beds have been productive.^[7] Plant fossils and trace fossils have been unearthed here too.^[8][9][10]

Lithology

The Wapiti Formation consists of interbedded sandstones, siltstones, shales and mudstones, with thin conglomerates, coal seams and bentonite beds. The sandstones are typically thick, pale grey, crossbedded and bentonitic. The middle part contains less sandstones, more mudstones, and fewer and thinner coals. The upper part contains thicker lenticular sandstones and more coals.^[4]

Depositional environment

The Wapiti Formation was deposited in inland fluvial and floodplain environments, with local areas of lacustrine sediments.^[11] The sandstones were deposited mainly in fluvial channel environments, with siltstones, carbonaceous shales and coals accumulating in overbank settings.

Thickness and Distribution

The Wapiti Formation rests conformably on the marine shales of the Smoky Group. It is more than 1,300 m (4,300 ft) thick in the foothills of the Canadian Rockies in the west,^[11] and it thins eastward to its erosional edge.^[12] It is correlative with the entire sequence of the Belly River Group, Bearpaw Formation, Edmonton Group and Scollard Formation in south-central Alberta.^[11] In most areas it is unconformably overlain by glacial and post-glacial sediments of Quaternary age, or exposed at surface. In a few upland areas it is unconformably overlain by Paleogene gravel deposits.^[4]

Vertebrate paleofauna

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Indeterminate ankylosaurids, albertosaurines, pachycephalosaurids, ornithomimids, and saurolophines are known from Alberta.^[13][14] Corythosaurus is also known from the formation.^[15]

Dinosaurs of the Wapiti Formation
Genus	Species	Location	Member	Material	Notes	Images
cf. Albertosaurus[16]	Indeterminate	British Columbia		Teeth
cf. Gorgosaurus[17]	Indeterminate	Alberta		Teeth
Bellatoripes	B. fredlundi	Alberta	Unit 4	Three trackways and an isolated print.	Footprints of large tyrannosaurids.
cf. Haenamichnus[18]	cf. H. isp.	Alberta	Unit 4	An isolated track.	Footprint of large azhdarchid pterosaur.
Boreonykus[19]	B. certekorum	Alberta	Unit 3			Boreonykus certekorum
Troodon[20]	Indeterminate	Alberta	Units 3 and 4[21]	Teeth; probable troodontid footprints are also known[21]
Edmontosaurus[22]	Edmontosaurus regalis	Alberta	Unit 4			Edmontosaurus regalis
Hadrosauridae nov. tax.[16]	sp. nov.	British Columbia			A new taxon of hadrosaurid.
Pachyrhinosaurus[14]	P. lakustai	Alberta				Pachyrhinosaurus lakustai
Richardoestesia[13]	R. gilmorei	Alberta
Saurornitholestes[13]	S. sp.	Alberta

See also

• List of dinosaur-bearing stratigraphic units