Lance Formation

The Lance (Creek) Formation is a division of Late Cretaceous (dating to about 69–65.5 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 South Dakota and, the Frenchman Formation of southwest Saskatchewan, and the lower part of the Scollard Formation of Alberta.

The Lance Formation occurs above the Baculites clinolobatus ammonite marine zone in Wyoming, the top of which has been dated to about 69 million years ago, and extends to the K-Pg boundary, 65.5 million years ago. However, the characteristic land vertebrate fauna of the Lancian age (which take its name from this formation) is only found in the upper strata of the Lance, roughly corresponding to the thinner equivalent formations such as the Hell Creek Formation, the base of which has been estimated at 167 years old.

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.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.

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

Depositional environment 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.

Paleontology 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.Silver, Mark (August 2, 2014) "The Dinosaur Surveyors" The American Surveyor Frederick Maryland Most other 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

Birds Birds reported from the Lance Formation Genus Species Location Stratigraphic Position Material Notes ImagesApatornisA. retususReclassified as Palintropus retususCeramornisC. major UCMP 53959 (holotype), a partial coracoidA possible charadriiform birdCimolopteryxC. petraReclassified as Lamarqueavis minimaC. rara YPM 1805 (holotype), a partial coracoidA charadriiformC. retusaReclassified as Palintropus retususC. minimaReclassified as Lamarqueavis minima"Cimolopteryx""C." maxima UCMP 53973 (holotype), a partial coracoidA charadriiform bird, not necessarily closely related to Cimolopteryx.GraculavusG. augustus AMNH 25223, a partial humerusA possible charadriiformLamarqueavisL. minima UCMP 53976 (holotype), a partial coracoidA charadriiformL. petra AMNH 21911 (holotype), a partial coracoidA charadriiformLonchodytesL. estesi UCMP 53954 (holotype), a partial tarsometatarsusA possible procellariiform"Lonchodytes""L." pterygius UCMP 53961 (holotype), a partial carpometacarpusA possible charadriiform"Palaeotringa""P." vetus ANSP 13361 (holotype), a partial tibiotarsus AMNH 25221, a partial tibiotarsusA bird similar to gruids, idiornithids and presbyornithids.PalintropusP. retusus YPM 513 (holotype), a partial coracoidA basal ornithuromorph belonging to Ambiortiformes.PotamornisP. skutchi UCMP 73103 (holotype), a quadrate tarsometatarsus?"Table 11.1," in Weishampel, et al. (2004). Page 215.A hesperornithiform possibly also present in the Hell Creek Formation.TorotixT. clemensi UCMP 53958, a partial humerusA possible pelecaniformUnnamed presbyornithidIndeterminate AMNH 21929, a partial scapula AMNH 22603, a partial scapula YPM 868, a partial scapula AMNH 22602, a partial sternumA presbyornithidUnnamed enantiornitheanUnnamed USNM 2909, a partial metatarsal and pedal phalangesAn enantiornithean, previously referred to "Ornithomimus" minutusUnnamed avianIndeterminate UCMP 53960, two partial neck vertebraeAn indeterminate avianUnnamed phalacrocoracidIndeterminate AMNH 25272, a femurA possible phalacrocoracidUnnamed galloanserineIndeterminate UCMP 53969, a quadrate YPM VP 59473, a partial skeleton consisting of skull, vertebrae and limb materialA possible galloanserine"Unnamed ornithurine A"Indeterminate UCMP 53962, a partial coracoid UCMP 53963, a partial coracoid AMNH uncatalogued, a partial coracoidOriginally thought to belong to Cimolopteryx rara, but probably a new species. Also present in the Frenchman Formation."Unnamed ornithurine C"Indeterminate YPM PU 17020, a partial coracoidAlso present in the Hell Creek Formation."Unnamed ornithurine E"Indeterminate USNM 181923, a partial coracoid USNM 13011, a partial coracoidAlso present in the Hell Creek Formation."Unnamed ornithurine F"Indeterminate UCMP 53957, a partial coracoid ACM 12359, a partial coracoidOriginally thought to belong to "Cimolopteryx" maxima, but probably a new species."Asteriornis-like bird"IndeterminateUCMP 143274, a fragmentary mandiblePreviously identified as a parrot, then Caenagnathidae, but lacks the distinctive mandibular grooves, which appear early in development and present even in the smallest members of the latter. Larger than Asteriornis itself.

Other coelurosaurs An isolated tooth crown of an indeterminate coelurosaur is recovered from the formation. Miscellaneous coelurosaurs of the Lance Formation Genus Species Location Stratigraphic Position Material Notes ImagesAublysodonA. amplusTeeth, type specimenDubious tyrannosaurids probably synonymous with Tyrannosaurus rexA. cristatusTeeth, type specimen"Ornithomimus""O." sedens"Sacrum and fragmentary illium""Table 6.1," in Weishampel, et al. (2004). Page 139. type specimenAn ornithomimid.ParonychodonP. caperatusTeeth, type specimenA troodontidPectinodonP. bakkeriTeeth, type specimenA troodontidTyrannosaurusT. rexSeveral partial specimens and teethA tyrannosaurid originally identified from the Hell Creek Formation. Also found in the Denver, Ferris, Frenchman, Javelina, Livingston, McRae, North Horn, Scollard, and Willow Creek Formations. Synonyms with type specimens from this formation include Dynamosaurus imperiosus and Manospondylus gigas.Trierarchuncuscf. T. prairiensisYPM VP 56916, complete manual ungual I YPM VP 57236, complete pedal ungual YPM VP 57402, partial pedal ungualAn alvarezsaurid originally identified from the Hell Creek Formation.TroodontinaeIndeterminateYPM VP 004691Not referrable to Paronychodon or Pectinodon.cf. MicroraptoriaIndeterminateYPM 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 vertebraPotentially the youngest microraptorian specimens, but YPM VP 865 may belong to the Unenlagiinae or Halszkaraptorinae.EudromaeosauriaIndeterminateYPM VPPU 20589NanotyrannidaeIndeterminateYPM 55587

Ornithischia

Ankylosaurs Ankylosaurs of the Lance Formation Genus Species Location Stratigraphic Position Material Notes ImagesAnkylosaurusA. magniventris The Dinosauria 2nd Edition (David B. Weishampel, Halszka Osmólska and Peter Dodson), p. 584-585, Dinosaur Distribution (DAVID B. WEISHAMPEL, PAUL M. BARRETT, RODOLFO A. CORIA, JEAN LE LOEUFF, XU XING, ZHAO XIJIN, ASHOK SAHNI, ELIZABETH M. P. GOMANI, CHRISTOPHER R. NOTO) Wyoming More than 70 osteoderms and a toothAn ankylosaurid, originally identified from the Hell Creek Formation.DenversaurusD. schlessmaniWyomingFPDM-V9673, formerly BHI 127327A nodosaurid, originally identified from the Hell Creek Formation.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).EdmontoniaE. sp. WyomingTeethA nodosaurid. Fossils have been unearthed in the Hell Creek Formation, the Ferris Formation, the Dinosaur Park Formation, the Horseshoe Canyon Formation, and the Denver Formation."Palaeoscincus""P. latus" WyomingTeethProbably a nodosaurid, but the teeth could also belong to the Pachycephalosauridae.

Marginocephalians Marginocephalians reported from the Lance Formation Genus Species Location Stratigraphic Position Material Notes ImagesAgathaumasA. sylvestris"Partial sacrum and pelvis,""Table 23.1," in Weishampel, et al. (2004). Page 496. type specimen.A dubious ceratopsid probably synonymous with Triceratops horridusLeptoceratopsL. gracilisA ceratopsianNedoceratopsN. hatcheri"[One] skull," type specimen.A ceratopsid possibly synonymous with Triceratops horridus. Synonyms include Diceratops hatcheri and Diceratus hatcheri.PachycephalosaurusP. wyomingensisFragmentary specimens including the type specimen.A pachycephalosaur. Synonyms with type specimens from this formation include Troodon wyomingensis."Palaeoscincus""P." latus"Tooth.""Table 17.1," in Weishampel, et al. (2004). Page 368.A dubious pachycephalosaur, previously classified as the ankylosaur PalaeoscincusStygimolochS. spiniferA pachycephalosaur possibly synonymous with Pachycephalosaurus wyomingensisTorosaurusT. latusSeveral specimens including the type specimen.A ceratopsid possibly synonymous with Triceratops horridus. Torosaurus gladius, with type specimen from this formation, is a synonym. Also present in the Frenchman and Hell Creek Formations.TriceratopsT. horridus"Partial skull and skeleton," type specimenA ceratopsid, also found in the Evanston, Frenchman, Hell Creek, Laramie, and Scollard Formations. Synonyms with type specimens from this formation include T. ingens and T. sulcatus.

Ornithopods Indeterminate lambeosaurinae fossils have been found in the Lance Formation. Ornithopods of the Lance Formation Genus Species Location Stratigraphic Position Abundance Notes ImagesEdmontosaurusE. annectensSkull, skeletons, including the type specimen, "mummy", and a bone bed.A hadrosaurid. Synonyms from this formation include Anatosaurus annectens and Claosaurus annectens. Also found in the Frenchman, Hell Creek, Laramie and Scollard Formations.ThescelosaurusT. neglectusWell-preserved skeleton, type specimen A thescelosaurid. Also found in the Frenchman, Hell Creek, Laramie and Scollard Formations.ThespesiusT. occidentalisTeeth, vertebrae, toe bone (including type specimen)A dubious hadrosaurid possibly synonymous with E. annectens"Trachodon""T." longicepsOne partial jaw (YPM 616), type specimenA dubious hadrosaurid possibly synonymous with E. annectens

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

Remains of fishes and mammals (i.e. Nanocuris) have also been found in the Lance Formation.

Lance Formation

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