Lance Formation Stratigraphic range: Upper Maastrichtian, 67.5–65.5 Ma |
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Badlands in the Lance Formation along Cow Creek near the type locality. Niobrara County, Wyoming |
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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.
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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.
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.
UCMP 143274 (Caenagnathidae?)[2]
Color key
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Notes Uncertain or tentative data are in small text; |
Birds reported from the Lance Formation | ||||||
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Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
A. retusus |
Partial coracoid |
Reclassified as Palintropus retusus |
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C. major |
Partial coracoid |
A possible charadriiform |
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C. maxima |
A charadriiform, also present in the Hell Creek Formation |
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C. petra |
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C. rara |
A charadriiform, also present in the Frenchman Formation |
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C. retusa |
Partial coracoid |
Reclassified as Palintropus retusus |
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"Cimolopteryx" |
"C." minima |
A charadriiformes previously referred to Cimolopteryx but belonging to a new genus. Also present in the Hell Creek Formation |
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G. augustus |
Partial humerus |
A possible charadriiform |
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I.? sp. |
Partial sacrum |
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L. estesi |
Partial tarsometatarsus |
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"Lonchodytes" |
"L." pterygius |
Partial carpometacarpus |
A neoavian, formerly classified as Lonchodytes |
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"Palaeotringa" |
"P." vetus |
Two partial tibiotarsi |
A bird similar to gruids, idiornithids and presbyornithids. Formerly classified as Palaeotringa |
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P. retusus |
Partial coracoid |
A possible galliform |
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P. skutchi |
"Quadrate and postcranial elements."[3] |
An ornithurine, possibly a hesperornithiform |
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Presbyornithidae indet. |
Indeterminate |
Three partial shoulder blades and a partial breastbone |
A presbyornithid[4] |
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T. clemensi |
Partial humerus |
A possible charadriiform or pelecaniform |
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Unnamed enantiornithine |
Unnamed |
Partial MTII and pedal phalanges |
An enantiornithine, previously referred to "Ornithomimus" minutus[5] |
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Unnamed neornithine |
Unnamed |
Two fragmentary neck vertebrae |
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Unnamed phalacrocoracid |
Unnamed |
Femur |
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Unnamed psittaciform |
Unnamed |
Lower jaw |
Misc Coelurosaurs of the Lance Formation | ||||||
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Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
A. amplus |
Nomina dubia probably synonymous with Tyrannosaurus rex |
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A. cristatus |
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Indeterminate |
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D. cristatus |
"Tooth."[7] |
Junior synonym of Troodon formosus, actually from the Judith River Formation |
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Indeterminate |
Teeth |
Tyrannosaur teeth previously referred to Dryptosaurus |
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D. imperiosus |
Junior synonym of Tyrannosaurus rex |
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M. gigas |
Neck vertebrae |
Nomen dubium probably synonymous with Tyrannosaurus rex |
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Indeterminate |
An ornithomimid |
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O. sedens |
Reclassified as Struthiomimus sedens |
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"Ornithomimus" |
"O.". minutus |
Misclassified as the former Ornithomimus species now recognized as an alvarezsaurid from the Denver Basin, material actually belonged to an enantiornithine |
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P. caperatus |
Teeth |
A troodontid |
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P. bakkeri |
Teeth |
Junior synonym of Troodon formosus |
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R. cf. gilmorei |
Teeth |
Dromaeosaurids |
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R.? isosceles |
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Indeterminate |
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S. inequalis |
Teeth |
Misclassified as Troodon inequalis, from the Dinosaur Park Formation |
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S. sedens |
"Sacrum and fragmentary illium."[8] |
An ornithomimid |
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T. bakkeri |
Teeth |
Junior synonym of T. formosus |
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T. formosus |
Teeth |
A troodontid, also found in the Dinosaur Park, Judith River, Oldman and Two Medicine Formations |
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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. |
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Unnamed dromaeosaurid |
Unnamed (Ostrom, 1969) |
Teeth |
A dromaeosaurid |
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Unnamed troodontid |
Unnamed (Currie, Rigby and Sloan, 1990) |
Teeth |
A troodontid |
Ankylosaurs of the Lance Formation | ||||||
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Genus | Species | Location | Stratigraphic Position | Abundance | Notes | Images |
A. magniventris |
An ankylosaurid |
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D. schlessmani |
Reclassified as Edmontonia schlessmani[9] |
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E. rugosidens |
Material classified as E. schlessmani is sometimes considered to be conspecific with E. rugosidens[9] |
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E. schlessmani[10] |
Marginocephalians reported from the Lance Formation | ||||||
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Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
A. sylvestris |
"Partial sacrum and pelvis."[11] |
A dubious ceratopsid probably synonymous with Triceratops |
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D. hatcheri |
Junior synonym of Nedoceratops hatcheri |
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L. gracilis |
A ceratopsian |
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N. hatcheri |
"[One] skull."[11] |
A ceratopsid possibly synonymous with Triceratops[12] |
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P. wyomingensis |
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"Palaeoscincus" |
"P." latus |
"Tooth."[13] |
A dubious pachycephalosaur, previously classified as the ankylosaur Palaeoscincus |
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S. spinifer |
A pachycephalosaur possibly synonymous with Pachycephalosaurus wyomingensis[14] |
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T. latus |
A ceratopsid possibly synonymous with Triceratops.[12] Also present in the Frenchman and Hell Creek Formations. |
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T. horridus |
"Partial skull and skeleton."[11] |
A ceratopsid, also found in the Evanston, Frenchman, Kirtland, Hell Creek, Laramie, and Scollard Formations. |
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T. ingens |
Junior synonym of T. horridus |
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T. sulcatus |
"Fragmentary skull."[11] |
A nomen dubium |
Ornithopods of the Lance Formation | ||||||
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Genus | Species | Location | Stratigraphic Position | Abundance | Notes | Images |
A. annectens |
Reclassified as Edmontosaurus annectens |
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A. longiceps |
A dubious hadrosaurid, probably synonymous with Edmontosaurus annectens |
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C. annectens |
Reclassified as Edmontosaurus annectens |
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E. annectens |
A hadrosaurid |
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E. regalis |
Misidentified E. annectens remains[15] |
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T. neglectus |
A "hypsilophodont".[16] Also found in the Frenchman, Hell Creek, Laramie and Scollard Formations. | |||||
T. annectens |
Reclassified as Edmontosaurus annectens |
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T. occidentalis |
A dubious hadrosaurid |
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T. annectens |
Reclassified as Edmontosaurus annectens |
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T. longiceps |
Reclassified as Anatotitan longiceps, possibly synonymous with Anatotitan copei and/or Edmontosaurus annectens |
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.