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The Lance (Creek) Formation is a group of rocks from the Late Cretaceous time, about 69 to 66 million years ago, found in the western United States. It was named after Lance Creek, Wyoming. This formation is important because it has many fossils. These fossils help scientists learn about life near the end of the Mesozoic era.
The Lance Formation is from a time called the Late Maastrichtian, also known as the Lancian age. It shares many animals with other famous rock layers. These include the Hell Creek Formation in Montana and North Dakota, the Frenchman Formation in southwest Saskatchewan, and the lower part of the Scollard Formation in Alberta.
These rocks sit above a layer marked by a sea creature called Baculites clinolobatus. This creature lived about 69 million years ago. The Lance Formation goes up to the time of a big event, called the K-Pg boundary, which happened 66 million years ago. Many famous animal fossils from this time are found in the upper parts of the Lance Formation. These fossils are close in age to the top layers of the Hell Creek Formation, which began about 66.8 million years ago.
Description
The Lance Formation is made of thick, buff-colored sandstone and drab to green shale. It dates back to the Upper Cretaceous period.
The formation's thickness varies. It measures about 90 meters (300 feet) in North Dakota and reaches nearly 600 meters (2,000 feet) in some parts of Wyoming. It was formed by streams on a coastal plain near the edge of the Western Interior Seaway. The climate at that time was subtropical, without cold seasons and likely received plenty of precipitation.
Paleontology
The Lance Formation is famous for its many fossils from the Late Cretaceous period, about 69 to 66 million years ago. Scientists have found lots of animal bones, including tiny pieces and even whole dinosaur skeletons. These fossils show many different creatures, from birds and pterosaurs like Quetzalcoatlus to fishes, mammals, and reptiles such as crocodiles and lizards. Some fossils are from animals that lived in freshwater, like frogs and salamanders, while others show that the sea was nearby.
The Lance Formation also includes marine fossils and many different types of dinosaurs, such as ankylosaurs and ornithopods. Some early birds found here are related to birds that live today, making this area very important for learning about life near the end of the dinosaur era.
| Birds reported from the Lance Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Material | Images | |||
A. retusus | ||||||
C. major | UCMP 53959 (holotype), a partial coracoid | |||||
C. petra | ||||||
C. rara | YPM 1805 (holotype), a partial coracoid | |||||
C. retusa | ||||||
C. minima | ||||||
"Cimolopteryx" | "C." maxima | UCMP 53973 (holotype), a partial coracoid | ||||
G. augustus | AMNH 25223, a partial humerus | |||||
L. minima | UCMP 53976 (holotype), a partial coracoid | |||||
L. petra | AMNH 21911 (holotype), a partial coracoid | |||||
L. estesi | UCMP 53954 (holotype), a partial tarsometatarsus | |||||
"Lonchodytes" | "L." pterygius | UCMP 53961 (holotype), a partial carpometacarpus | ||||
"P." vetus | ANSP 13361 (holotype), a partial tibiotarsus AMNH 25221, a partial tibiotarsus | |||||
P. retusus | YPM 513 (holotype), a partial coracoid | |||||
P. skutchi | UCMP 73103 (holotype), a quadrate tarsometatarsus? | |||||
T. clemensi | UCMP 53958, a partial humerus | |||||
Unnamed presbyornithid | Indeterminate | AMNH 21929, a partial scapula AMNH 22603, a partial scapula YPM 868, a partial scapula AMNH 22602, a partial sternum | ||||
Unnamed enantiornithean | Unnamed | USNM 2909, a partial metatarsal and pedal phalanges | ||||
Unnamed avian | Indeterminate | UCMP 53960, two partial neck vertebrae | ||||
Unnamed phalacrocoracid | Indeterminate | AMNH 25272, a femur | ||||
Unnamed galloanserine | Indeterminate | UCMP 53969, a quadrate YPM VP 59473, a partial skeleton consisting of skull, vertebrae and limb material | ||||
"Unnamed ornithurine A" | Indeterminate | UCMP 53962, a partial coracoid UCMP 53963, a partial coracoid AMNH uncatalogued, a partial coracoid | ||||
"Unnamed ornithurine C" | Indeterminate | YPM PU 17020, a partial coracoid | ||||
"Unnamed ornithurine E" | Indeterminate | USNM 181923, a partial coracoid USNM 13011, a partial coracoid | ||||
"Unnamed ornithurine F" | Indeterminate | UCMP 53957, a partial coracoid ACM 12359, a partial coracoid | ||||
| "Asteriornis-like bird" | Indeterminate | UCMP 143274, a fragmentary mandible | ||||
| Miscellaneous coelurosaurs of the Lance Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Material | Images | |||
A. amplus | Teeth, type specimen | |||||
A. cristatus | Teeth, type specimen | |||||
"O." sedens | "Sacrum and fragmentary illium" type specimen | |||||
P. caperatus | Teeth, type specimen | |||||
P. bakkeri | Teeth, type specimen | |||||
T. rex | Several partial specimens and teeth | |||||
| Trierarchuncus | cf. T. prairiensis | YPM VP 56916, complete manual ungual I YPM VP 57236, complete pedal ungual YPM VP 57402, partial pedal ungual | ||||
| Troodontinae | Indeterminate | YPM VP 004691 | ||||
| cf. Microraptoria | Indeterminate | YPM VP 865, distal half of metatarsal III YPM VP 57403, ?left pedal ungual II-3 YPM VP 57404, ?left pedal phalanx II-1 YPM VP 57237, distal caudal vertebra | ||||
| Eudromaeosauria | Indeterminate | YPM VPPU 20589 | ||||
| Ankylosaurs of the Lance Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Material | Images | ||
A. magniventris | Wyoming | More than 70 osteoderms and a tooth | ||||
| Denversaurus | D. schlessmani | Wyoming | FPDM-V9673, formerly BHI 127327 | |||
E. sp. | Wyoming | Teeth | ||||
"P. latus" | Wyoming | Teeth | ||||
| Marginocephalians reported from the Lance Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Material | Images | |||
A. sylvestris | "Partial sacrum and pelvis," type specimen. | |||||
L. gracilis | ||||||
N. hatcheri | "[One] skull," type specimen. | |||||
P. wyomingensis | Fragmentary specimens including the type specimen. | |||||
"Palaeoscincus" | "P." latus | "Tooth." | ||||
S. spinifer | ||||||
T. latus | Several specimens including the type specimen. | |||||
T. horridus | "Partial skull and skeleton," type specimen | |||||
| Ornithopods of the Lance Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Abundance | Images | |||
E. annectens | Skull, skeletons, including the type specimen, "mummy", and a bone bed. | |||||
T. neglectus | Well-preserved skeleton, type specimen | |||||
T. occidentalis | Teeth, vertebrae, toe bone (including type specimen) | |||||
"T." longiceps | One partial jaw (YPM 616), type specimen | |||||
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