Lance Formation

Lance Formation Stratigraphic range: Upper Maastrichtian, 67.5–65.5 Ma PreЄ Є O S D C P T J K Pg N ↓
Badlands in the Lance Formation along Cow Creek near the type locality. Niobrara County, Wyoming
Type	Sedimentary
Underlies	Fort Union Formation
Overlies	Meeteetse Formation
Thickness	up to 600 metres (1,970 ft)
Lithology
Primary	Sandstone, siltstone, shale
Location
Named for	Lance Creek, Wyoming
Region	Wyoming
Country	United States

The Lance (Creek) Formation is a division of Late Cretaceous (dating to about 67.5-65.5 Ma) rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas. The Lance Formation is Late Maastrichtian in age (Lancian land mammal age), and shares much fauna with the Hell Creek Formation of Montana and North Dakota, the Frenchman Formation of southwest Saskatchewan, and the lower part of the Scollard Formation of Alberta.

1 Description
2 Paleontology
3 See also
4 Footnotes
5 External links

Description

The formation is described by W.G. Pierce as thick-bedded, buff-colored sandstone, and drab to green shale. It is Upper Cretaceous in age.^[1]

The formation varies in thickness from about 90m (300 feet) in North Dakota, to almost 600m (2,000 feet) in parts of Wyoming.

At least tens of thousands of Late Cretaceous vertebrate remains have been recovered from the Lance Formation. Fossils ranging from microscopic elements to extensive bonebeds, with nearly complete, sometimes articulated dinosaur skeletons, have been found.

Paleontology

The Lance Formation was laid down by streams, on a coastal plain along the edge of the Western Interior Seaway. The climate was subtropical; there was no cold season and probably ample precipitation. Most of the animals known from the formation are freshwater animals, and some are exclusively freshwater forms (for instance, frogs and salamanders). However, marine fossils are also found in the formation, suggesting that the sea was nearby. The bird fauna is mainly composed of orders still existing today.

Coelurosaurs

UCMP 143274 (Caenagnathidae?)^[2]

Color key

Taxon	Reclassified taxon	Taxon falsely reported as present	Dubious taxon or junior synonym	Ichnotaxon	Ootaxon	Morphotaxon

Notes
Uncertain or tentative data are in small text; ~~crossed out~~ data are discredited.

Birds

Birds reported from the Lance Formation
Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Apatornis	A. retusus			Partial coracoid	Reclassified as Palintropus retusus
Ceramornis	C. major			Partial coracoid	A possible charadriiform
Cimolopteryx	C. maxima				A charadriiform, also present in the Hell Creek Formation
	C. petra
	C. rara				A charadriiform, also present in the Frenchman Formation
	C. retusa			Partial coracoid	Reclassified as Palintropus retusus
"Cimolopteryx"	"C." minima				A charadriiformes previously referred to Cimolopteryx but belonging to a new genus. Also present in the Hell Creek Formation
Graculavus	G. augustus			Partial humerus	A possible charadriiform
Ichthyornis?	I.? sp.			Partial sacrum	An ichthyornithiform
Lonchodytes	L. estesi			Partial tarsometatarsus	A procellariiform
"Lonchodytes"	"L." pterygius			Partial carpometacarpus	A neoavian, formerly classified as Lonchodytes
"Palaeotringa"	"P." vetus			Two partial tibiotarsi	A bird similar to gruids, idiornithids and presbyornithids. Formerly classified as Palaeotringa
Palintropus	P. retusus			Partial coracoid	A possible galliform
Potamornis	P. skutchi			"Quadrate and postcranial elements."^[3]	An ornithurine, possibly a hesperornithiform
Presbyornithidae indet.	Indeterminate			Three partial shoulder blades and a partial breastbone	A presbyornithid^[4]
Torotix	T. clemensi			Partial humerus	A possible charadriiform or pelecaniform
Unnamed enantiornithine	Unnamed			Partial MTII and pedal phalanges	An enantiornithine, previously referred to "Ornithomimus" minutus^[5]
Unnamed neornithine	Unnamed			Two fragmentary neck vertebrae	A neornithine^[4]
Unnamed phalacrocoracid	Unnamed			Femur	A phalacrocoracid^[4]
Unnamed psittaciform	Unnamed			Lower jaw	A possible parrot^[6]

Other Coelurosaurs

Misc Coelurosaurs of the Lance Formation
Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Aublysodon	A. amplus				Nomina dubia probably synonymous with Tyrannosaurus rex
Aublysodon	A. cristatus				Nomina dubia probably synonymous with Tyrannosaurus rex
Dromaeosaurus	Indeterminate				A dromaeosaurid
?Dryptosaurus	D. cristatus			"Tooth."^[7]	Junior synonym of Troodon formosus, actually from the Judith River Formation
?Dryptosaurus	Indeterminate			Teeth	Tyrannosaur teeth previously referred to Dryptosaurus
Dynamosaurus	D. imperiosus				Junior synonym of Tyrannosaurus rex
Manospondylus	M. gigas			Neck vertebrae	Nomen dubium probably synonymous with Tyrannosaurus rex
Ornithomimus	Indeterminate			An ornithomimid
Ornithomimus	O. sedens				Reclassified as Struthiomimus sedens
"Ornithomimus"	"O.". minutus				Misclassified as the former Ornithomimus species now recognized as an alvarezsaurid from the Denver Basin, material actually belonged to an enantiornithine
Paronychodon	P. caperatus			Teeth	A troodontid
Pectinodon	P. bakkeri			Teeth	Junior synonym of Troodon formosus
Ricardoestesia	R. cf. gilmorei			Teeth	Dromaeosaurids
	R.? isosceles
	Indeterminate
Saurornithoides	S. inequalis			Teeth	Misclassified as Troodon inequalis, from the Dinosaur Park Formation
Struthiomimus	S. sedens			"Sacrum and fragmentary illium."^[8]	An ornithomimid
Troodon	T. bakkeri			Teeth	Junior synonym of T. formosus
Troodon	T. formosus			Teeth	A troodontid, also found in the Dinosaur Park, Judith River, Oldman and Two Medicine Formations
Tyrannosaurus	T. rex			Several partial specimens and teeth	A tyrannosaurid, also found in the Denver, Ferris, Frenchman, Hell Creek, Javelina, Kirtland, Livingston, McRae, North Horn, Scollard, Tornillo, and Willow Creek Formations.
Unnamed dromaeosaurid	Unnamed (Ostrom, 1969)			Teeth	A dromaeosaurid
Unnamed troodontid	Unnamed (Currie, Rigby and Sloan, 1990)			Teeth	A troodontid

Ornithischia

Ankylosaurs

Ankylosaurs of the Lance Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes	Images
Ankylosaurus	A. magniventris				An ankylosaurid
Denversaurus	D. schlessmani				Reclassified as Edmontonia schlessmani^[9]
Edmontonia	E. rugosidens				Material classified as E. schlessmani is sometimes considered to be conspecific with E. rugosidens^[9]
Edmontonia	E. schlessmani^[10]				A nodosaurid

Marginocephalians

Marginocephalians reported from the Lance Formation
Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Agathaumas	A. sylvestris			"Partial sacrum and pelvis."^[11]	A dubious ceratopsid probably synonymous with Triceratops
Diceratus	D. hatcheri				Junior synonym of Nedoceratops hatcheri
Leptoceratops	L. gracilis				A ceratopsian
Nedoceratops	N. hatcheri			"[One] skull."^[11]	A ceratopsid possibly synonymous with Triceratops^[12]
Pachycephalosaurus	P. wyomingensis				A pachycephalosaur
"Palaeoscincus"	"P." latus			"Tooth."^[13]	A dubious pachycephalosaur, previously classified as the ankylosaur Palaeoscincus
Stygimoloch	S. spinifer				A pachycephalosaur possibly synonymous with Pachycephalosaurus wyomingensis^[14]
Torosaurus	T. latus				A ceratopsid possibly synonymous with Triceratops.^[12] Also present in the Frenchman and Hell Creek Formations.
Triceratops	T. horridus			"Partial skull and skeleton."^[11]	A ceratopsid, also found in the Evanston, Frenchman, Kirtland, Hell Creek, Laramie, and Scollard Formations.
	T. ingens				Junior synonym of T. horridus
	T. sulcatus			"Fragmentary skull."^[11]	A nomen dubium

Ornithopods

Ornithopods of the Lance Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes	Images
Anatosaurus	A. annectens				Reclassified as Edmontosaurus annectens
Anatotitan	A. longiceps				A dubious hadrosaurid, probably synonymous with Edmontosaurus annectens
Claosaurus	C. annectens				Reclassified as Edmontosaurus annectens
Edmontosaurus	E. annectens				A hadrosaurid
Edmontosaurus	E. regalis				Misidentified E. annectens remains^[15]
Thescelosaurus	T. neglectus				A "hypsilophodont".^[16] Also found in the Frenchman, Hell Creek, Laramie and Scollard Formations.
Thespesius	T. annectens				Reclassified as Edmontosaurus annectens
Thespesius	T. occidentalis				A dubious hadrosaurid
Trachodon	T. annectens				Reclassified as Edmontosaurus annectens
Trachodon	T. longiceps				Reclassified as Anatotitan longiceps, possibly synonymous with Anatotitan copei and/or Edmontosaurus annectens

Other vertebrates

Other land vertebrates include pterosaurs (e.g. cf. Azhdarcho), crocodiles, champsosaurs, lizards, snakes, turtles, frogs and salamanders.

Remains of fishes and mammals have also been found in the Lance Formation.

Footnotes

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^ Pierce, W.G., 1997, Geologic map of the Cody 1 degree x 2 degrees quadrangle, northwestern Wyoming: U.S. Geological Survey, Miscellaneous Geologic Investigations Map I-2500, scale 1:250000.
^ Initially believed to be a parrot mandible. This is unlikely however, as all early parrots seem to have had straight beaks.
^ "Table 11.1," in Weishampel, et al. (2004). Page 215.
^ ^a ^b ^c Hope, 2002
^ Chiappe, L. M., and Walker, C. A. (2002) Skeletal morphology and systematics of the Cretaceous Euenantiornithes (Ornithothoraces: Enantiornithes): In: Mesozoic Birds, above the heads of Dinosaurs, University of California Press, 240-267.
^ Stidham, 1998
^ "Table 9.1," in Weishampel, et al. (2004). Page 186.
^ "Table 6.1," in Weishampel, et al. (2004). Page 139.
^ ^a ^b Vickaryous, M.K., Maryańska, T., and Weishampel, D.B., (2004). "Ankylosauria". In Weishampel, D. B., Dodson, P., and Osmólska, H. (eds.). The Dinosauria (Second Edition). University of California Press. pp. 363–392. ISBN 0-520-24209-2.
^ 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.(1988).
^ ^a ^b ^c ^d "Table 23.1," in Weishampel, et al. (2004). Page 496.
^ ^a ^b Scannella, J. and Horner, J.R. (2010). "Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny." Journal of Vertebrate Paleontology, 30(4): 1157 - 1168. doi:10.1080/02724634.2010.483632
^ "Table 17.1," in Weishampel, et al. (2004). Page 368.
^ Horner J.R. and Goodwin, M.B. (2009). "Extreme cranial ontogeny in the Upper Cretaceous Dinosaur Pachycephalosaurus." PLoS ONE, 4(10): e7626. Online full text
^ Campione, N.E. (2009). "Cranial variation in Edmontosaurus (Hadrosauridae) from the Late Cretaceous of North America." North American Paleontological Convention (NAPC 2009): Abstracts, p. 95a. PDF link
^ Boyd, Clint A.; Brown, Caleb M.; Scheetz, Rodney D.; and Clarke, Julia A. (2009). "Taxonomic revision of the basal neornithischian taxa Thescelosaurus and Bugenasaura". Journal of Vertebrate Paleontology 29 (3): 758–770. doi:10.1671/039.029.0328.

External links

Passport-In-Time Microvertebrate Fossil Project