Pierre Shale
Stratigraphic range: Campanian-Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N
A broken concretion with fossils inside; Late Cretaceous Pierre Shale near Ekalaka, Montana
Type	Geological formation
Sub-units	From oldest to youngest:[1] Gammon Ferruginous Member Sharon Springs Member Mitten Black Shale Member Red Bird Silty Member A lower unnamed shale member Kara Bentonitic Member Upper unnamed shale member
Underlies	Fox Hills Formation
Overlies	Niobrara Formation
Lithology
Primary	Shale
Location
Coordinates	44°23′42″N 100°24′43″W / 44.395°N 100.412°W / 44.395; -100.412
Region	North America
Country	United States,  Canada
Type section
Named for	Fort Pierre
Named by	Meek & Hayden, 1862
Pierre Shale (the United States) Show map of the United States Pierre Shale (South Dakota) Show map of South Dakota

The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from Pembina Valley in Canada^[2] to New Mexico.

The Pierre Shale was described by Meek and Hayden in 1862 in the Proceedings of the Academy of Sciences (Philadelphia). They described it as a dark-gray shale, fossiliferous, with veins and seams of gypsum, and concretions of iron oxide. The Pierre Shale is about 3,138 feet (956m) thick at the type locality. It overlies the Niobrara division and underlies the Fox Hills beds.^[1] It was named for an occurrence near Fort Pierre on the Missouri River in South Dakota.^[3]

The Pierre Shale is of marine origin and was deposited in the Western Interior Seaway. It is correlative with other marine shales that occur farther west, such as the Bearpaw Shale, Mancos Shale and the Lewis Shale.^[4] It correlates with the Lea Park Formation in central Alberta.^[5] The Pierre is overlain by marginal marine deposits of the Fox Hills Formation.

Most of the formation was deposited in the Campanian Age of the late Cretaceous. However, the discovery of fossils of Baculites baculus in the uppermost beds of the Pierre Shale in the Raton, New Mexico area show that deposition continued here into the early Maastrichtian.^[6]

Mineral resources

The Pierre Shale is the host formation for commercial petroleum deposits in the Florence and Canon City fields in Fremont County, Colorado, and the Boulder Oil Field in Boulder County, Colorado. More recently, natural gas has been extracted in the Raton Basin in southern Colorado. The shale formation is usually too impermeable for hydrocarbon extraction, but produces in areas where it is naturally fractured or fractured by artificial means.

Paleofauna

Reptiles

Dinosaurs

Birds reported from the Pierre Shale Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Brodavis	B. varneri	South Dakota	Sharon Springs Member.[7]		A hesperornithiform.
	B. sp.	Manitoba	Pembina Member.[7]		A hesperornithiform.
Hesperornis	H. bairdi	South Dakota	Sharon Springs Member.[7]		A hesperornithid.
	H. chowi	Manitoba & South Dakota	Pembina, Millwood, & Sharon Springs Members.[7]		A hesperornithid.
	H. lumgairi	Manitoba	Pembina Member.[7]		A hesperornithid.
	H. macdonaldi	Manitoba & South Dakota.	Gammon, Pembina, Millwood(?), & Sharon Springs Members.[7]		A hesperornithid.
	H. mengeli	Manitoba & South Dakota.	Pembina & Sharon Springs Members.[7]		A hesperornithid.
	H. regalis	Manitoba, South Dakota, & Kansas	Gammon, Pembina, & Sharon Springs Members.[7][8]		A hesperornithid.
	H. sp.	Manitoba.[8]	Pembina Member.[8]		Probably referrable to H. regalis, but indistinguishable from H. crassipes.[8]
Hesperornithidae	Gen. et. sp. indeterminate	Manitoba.[8]	Pembina Member.[8]	Multiple isolated synascra.[8]	A hesperornithid.
Hesperornithiformes	Fam., gen. et sp. indet.	Manitoba.[8]	Pembina Member.[8]	Multiple vertebrae, phalanges, tibiotarsal fragments and a fibula.[8]
Ichthyornis	I. sp.	Manitoba.[8]	Pembina Member.[8]	"MDM B77.03.07 (vertebral centrum), B80.05.14 (femur)".[8]	An ichthyornithe.

Ornithischians reported from the Pierre Shale Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Claosaurus	C. affinis	South Dakota.[9]		"Pedal phalanx (lost)."[10]	Currently considered dubious.

Mosasaurs

Mosasaurs reported from the Pierre Shale Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Clidastes	C. propython	Manitoba.[8]	Pembina Member.[8]	MDM M74.10.06 (skull, mandible, vertebral column).[8]	A mosasaurine also known from the Mooreville Chalk.
		Western Kansas.[11]		Vertebrae associated with 'Plesiosaurus' gulo currently lost.[12]	Likely represents the stomach contents of 'Plesiosaurus' gulo.[12]
Globidens	G. dakotensis	South Dakota.[13]	Sharon Springs Member.[13]	FMNH PR 846.[13]	A globidensin.
	G. schurmanni	At the Big Bend of the Missouri River, Buffalo County, South Dakota.[14]	Uppermost DeGrey Formation.[14]	"SDSM 74764, partial anterior skeleton, including cranium, jaws, cervical and trunk vertebrae partially articulated, pectoral girdles, partial anterior paddle, isolated humerus and ulna, and isolated caudal vertebrae".[14]
	G. sp.	Northwestern Logan County, Kansas.[13]	Upper level of the Sharon Springs Member.[13]	A nearly complete right dentary (FHSM VP–13828).[13]	A globidensin.
Hainosaurus	H. pembinensis	Near Morden, Manitoba.[15]	Pembina Member.[8][15]		Reassigned to the genus Tylosaurus.
Jormungandr	J. walhallaensis	Cavalier County, North Dakota.[16]	Pembina Member.[16]	Partial skull & skeleton.[16]	A mosasaurine.
Latoplatecarpus	L. nichollsae	"19 km northwest of Morden, Manitoba".[17]	Pembina Member.[17]	A skeleton (CMN 52261).[17]	A plioplatecarpine.
Mosasauridae	Subfam., gen. et. sp. indeterminate	Manitoba.[8]	Pembina Member.[8]	Fragmentary specimens consisting "mostly of vertebral scraps, ribs and flipper elements".[8]
Platecarpus	P. coryphaeus		Pembina Member.[8]		Now deemed synonymous with P. tympaniticus.
	P. ictericus		Pembina Member.[8]		Now deemed synonymous with P. tympaniticus.
	P. somenensis		Pembina Member.[8]		Found to nest within Latoplatecarpus nichollsae.
	P. tympaniticus		Pembina Member.[8]	Abundant specimens.[8]	A pliopatecarpine and the most abundant mosasaur of the Pierre Shale.
	P. sp.	Manitoba.[8]	Pembina Member.[8]	"Isolated skull elements, humeri and pectoral girdles".[8]	Probably referrable to P. tympaniticus based on size, but size alone is deemed insufficient for species identification.[8]
Plioplatecarpinae	Gen. et. sp. indeterminate	Manitoba.[8]	Pembina Member.[8]	Poorly preserved and unprepared remains.[8]
Plioplatecarpus	P. nichollsae	"19 km northwest of Morden, Manitoba".[17]	Pembina Member.[17]	A skeleton (CMN 52261).[17]	Reassigned to the genus Latoplatecarpus.[18]
Prognathodon	P. overtoni	South Dakota.[19]	Virgin Creek Member.[19]	KUVP 950 (the holotype for the species) and SDSM 3339.[19]	A mosasaurine also found in the Bearpaw Shale.
Tylosaurinae	Gen. et. sp. indet.	Manitoba.[8]	Pembina Member.[8]	Isolated limb and girdle elements (MDM M74.28.05, M75.20.06, M82.13.17, M84.09.18).[8]
Tylosaurus	T. pembinensis	Near Morden, Manitoba.[15]	Pembina Member.[15]		A tylosaurine.
	T. proriger	Manitoba.[8]	Pembina Member.[8]	MDM M77.17.07 quadrate, FMNH PR 591 quadrate, pubis, vertebrae.[8]	A tylosaurine.

Plesiosaurs