Species: formosus LEIDY, 1856
Etymology: Latin, forma, "shape."
= Stegoceras formosus (LEIDY, 1856)) emend GILMORE, 1924 (suggested)
Note: Though Gilmore (1924) did not specifically state Stegoceras formosus he did synonymize Tröödon formosus (Lambe) into Stegoceras validus as Tröödon validus. Brown & Schlaiker (1943) believed Stegoceras and Troödon were synonymous but kept T. validus and T. formosus as valid species.
= Stegoceras formosum (LEIDY, 1856) emend OLSHEVKY, 1991

Holotype: ANSP 9259

Locality: Badlands of the Judith River, Fergus County, Montana.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material: Tooth.

Referred material:

BASZIO, 1997

Locality: Alberta, Canada.

Horizon: Dinosaur Park Formation, upper Judith River Group.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

RTMP 79.8.1171, 88.50.58, 89.116.63, 89.76.50, 89.77.5, 89.89.4, 90.34.1: Teeth.

 

Locality: Stephen’s site, Wheatland County, Alberta Province, Canada.

Horizon: Horseshoe Canyon Formation (Lower Edmonton Formation), Edmonton Group.

Biostratigraphy:

Age: Edmontonian age, lower Maastrichtian Stage, Upper Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.

Material:

RTMP 1000-1004, 1032: Teeth.

Locality: Alberta, Canada.

Horizon: Scollard Formation, Uppermost Edmonton Group.

Biostratigraphy:

Age: Lancian Age, uppermost Maastrichtian Stage, uppermost Senonian subepoch, Upper Upper Gulf Epoch, Late Cretaceous.

Material:

JLE 64: 109: Tooth.

 

Locality:

Horizon: Lance Formation.

Biostratigraphy:

Age: Lancian Age, uppermost Maastrichtian Stage, uppermost Senonian subepoch, Upper Upper Gulf Epoch, Late Cretaceous.

Material:

UA BTB4b: 156, 157: Teeth.

BRINKMAN, 1990

Localities: BB 105 (3), BB 71 (2), BB 118 (1), BB 121 (1), BB 103 (3), BB 107 (1), BB 86 (4), BB 97 (3), BB 104 (1), BB 78 (1), BB 117 (1), BB 25 (3), BB 106 (1), BB 108 (4), BB 102 (2), BB 94 (1), BB 75 (1), BB 120 (3), BB 119 (2), BB 115 (1), Dinosaur Provincial Park, Newell County, Alberta Province, Canada.

Horizon: Dinosaur Park Formation, upper Judith River Group.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

Numbers: Not given: Teeth.

 

 

CURRIE, 1987

Locality: LSD 7, sec. 32, Tp. 20, R11, W4thM, north bonebed 74, Dinosaur Provincial Park, Newell County, Alberta Province, Canada.

Horizon: Dinosaur Park Formation, upper Judith River Group.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

RTMP 82.16.138: Partial edentulous dentary.

 

Locality: LSD 11, sec. 17, Twp 29, Rge. 20, W4thM, Bone Bed HC 1, Midland Provincial Park, Newell County, Alberta Province, Canada.

Horizon: Horseshoe Canyon Formation, Edmonton Group.

Biostratigraphy:

Age: Edmontonian age, lower Maastrichtian Stage, Upper Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.

Material:

RTMP 83.12.11: Fragmentary dentary.

In addition, more then 70 isolated teeth form the Judith River and Horseshoe Canyon Formation, Late Cretaceous, identified as Troodon and Pectinodon in the collections of the National Museum of Canada and Tyrrell Museum of Palaeontology.

CURRIE, RIGBY & SLOAN, 1990

Locality: Dinosaur Provincial Park, Newell County, Alberta Province, Canada.

Horizon: Dinosaur Park Formation, upper Judith River Group.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

TMP 83.45.7, 83.36.214: Maxillary teeth.

TMP 85.6.3: Premaxillary tooth.

TMP 83.36.215, 83.12.11, 82.20.23, 83.45.8, NMC 1267: Teeth.

 

DERSTLER, 1995

Locality: Dragons’ Grave, Niobrara County, Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

Age: Lancian age, upper Maastrichtian Stage, uppermost Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.

Material:

Numbers: Not given: Shed teeth.

 

EBERTH, BRAMAN, & TOKARK, 1990

Locality: Muddy Lake, Kindersley County, west-central Saskatchewan Province, Canada.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.

Material:

Number: Not given:

 

FIORILLO, & CURRIE, 1994

Localities: Antelope Head Quarry, Careless Creek Quarry, Emily’s Ankle Quarry, Top Cat Quarry, Hidden Valley Quarry, Wheatland and Golden Valley Counties, Central Montana.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

ANSP 15937, 15947, 15964, 17642, 17780, 17795, 18005: Teeth.
Note: Exact distribution not given.

ANSP 15950: Anterior maxillary tooth.

 

FIORILLO & GANGLOFF, (2000) 2001, FIORILLO, 2008

Locality: Liscomb Quarry (42 teeth), Sling Point Quarry (2 teeth), Byers Bed (tooth), Brooks Range, North Slope, Northern Alaska.

Horizon: Prince Creek Formation.

Biostratigraphy:

Age: Campanian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.

Material:

AK491-V-143, AK491-V-168, AK490-V-086FT, AK490-V-008FL, AK490-V-004, AK299-V-134, AK385-V-001, AK385-V-002, AK387-V-000FT, AK387-V-017, AK300-V-017, AK300-V-021, AK200-V0-042, AK300-V-055, AK300-V0129, AK300-V-060, AK383-V-018, AK383-V-183, AK383-V-137, AK383-V-140, AK383-V-176, AK382-V-015, AK383-V-105, AK233-V-054, AK392-V-007, AK284-V-024, AK285-V-008, AK285-V-013, AK285-V-037A, AK335-V-012FT, AK282-V-001, AK282-V-010, AK282-V-052, AK282-V-056, AK283-V-017, AK28S-V-115, AK497-V-002, AK498-V-001, AK498-V-002, AK498-V-003, AK83-V-095, AK335-V-076, AK459-V-011, AK388-V-002, AK388-V-082: Teeth.

FIORILLO, TYKOSKI, CURRIE, MCCARTHY & FLAIG, 2009

Locality: Liscomb Quarry, Brooks Range, North Slope, Northern Alaska.

Horizon: Prince Creek Formation.

Biostratigraphy:

Age: Campanian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.

Material:

AK-138-V-128: Partial braincase.

 

Locality: Magical Mystery Bar, Brooks Range, North Slope, Northern Alaska.

Horizon: Prince Creek Formation.

Biostratigraphy:

Age: Campanian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.

Material:

DMNH 22158: Fragmentary braincase.

SAHNI, 1972

Locality: Clambank Hollow, Montana.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

AMNH 8518, 8519, 8520: Teeth.

 

Locality:

Horizon:

Biostratigraphy:

Age:

Material:

MOR 430: Fragmentary skull?

 

JACKSON, HORNER & VARRICCHIO, 2010

Locality: Hill County, Montana.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

MOR 993: Egg with embryo

= Troodon cf. T. formosus NESOV, 1995, RICH, GANGLOFF & HAMMER, 1997, AVERIANOV & SUES, 2007

Locality: Kakanaut, left bank of the Koryak River, a tributary of the Kakanaut River near Lake Pekulneyskoje, 62?58’N, 176?E, Chukot Autonomous Area, Russia.

Horizon: Kakanaut Formation.

Biostratigraphy:

Age: Middle Maastrichtian Stage, Upper Senonian Subepoch, Upper Gulf Epoch, Late Cretaceous.

Material:

ZIN PH 1/28: Tooth.

 

RAMIREZ-VELASCO, & HERNANDEZ-RIVERA, 2015

(Romo de Vivar, 2011)

Locality: Ros 51, El Rosario, Baja California State, Mexico.

Horizon: El Gallo Formation.

Biostratigraphy:

Age: Late Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

IGM number not given: 2 teeth.

 

RYAN, RUSSELL, EBERTH & CURRIE, 2001

Locality: Centrosaurus bone bed (bone bed 43) Dinosaur Provinical Park, Alberta Province, Canada.

Horizon: Dinosaur Park Formation, upper Judith River Group.

Biostratigraphy:

Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.

Material:

Number: Not given:

 

 

= Troodon sp. cf. Troodon formosus STOKSA, 2005

Locality: Western South Dakota.

Horizon: Fox Hills Formation.

Biostratigraphy:

Age: Maastrichtian Stage, uppermost Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.

Material:

SDSM 14518: Dentary tooth.

STERNBERG, 1945

Locality:

Horizon:

Biostratigraphy:

Age:

Material:

GSC 8841: Tooth.

 

 

VARRICCHIO, 1993

Locality: MOR 553, Jack’s Birthday Site, located along Badger Creek, within the Blackfeet Indian Reservation, Museum of Rockies locality number TM-068, Sec. 11, T31N, R8W, Glacier County, Montana.

Horizon: Two Medicine Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material:

MOR 553-1: A large tibia.

MOR 553-7.24.8.64: A larger tibia.

MOR 563: Metatarsal and tibia of a small individual.

MOR 553-2: Intermediate-sized metatarsal.

MOR 533-1: 3 metatarsals of a large individual.

MOR 553-7.16.0.61: Femur.

 

VARRICCHIO, 1995

Locality: Jack’s Birthday Site, located along Badger Creek, within the Blackfeet Indian Reservation, Museum of Rockies locality number TM-068, Sec. 11, T31N, R8W, Glacier County, Montana.

Horizon: Two Medicine Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material:

Numbers: Not given:

VARRICCHIO & CURRIE, 1991, Material: Partial skeleton.

 

Oogenus: Prismatoolithus levus VARRICCHO, HORNER & JACKSON, 2002

Locality: Egg Island locality, Teton County, Montana.

Horizon: Two Medicine Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material:

MOR 246: Egg clutch with embryos.

MOR 246-1, -5, -7-11, -13, -16-19: Eggs with bones.

MOR 245-2, -4, -6, -12, -14, -15: Eggs.

VARRICCHIO, JACKSON, BORKOWSKI & HORNER, 1997

Locality: Egg Mountain, Teton County, northwestern Montana.

Horizon: Two Medicine Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material:

MOR 963: Nest with clutch of eggs.

FREIMUTH, VARRICCHIO, BRANNICK, WEAVER & WILSON MANTILLA, 2021

MOR 10913: Regurgitalite/gastric pellet with 16 maxillae, 33 dentaries, 15 indeterminate tooth-bearing fragments, 7 cranial fragments, 2 braincases, 9 long bone shafts (Alphadon halleyi), 1 lizard cranium, and 2 indeterminate lizard teeth.

MOR 10912: Regurgitalite/gastric pellet with 6 maxillae, 1 dentary, 1 ulan and 4 long bone shafts (Alphadon halleyi).

MOR 11750: Regurgitalite/gastric pellet with 3 dentries, 2 maxillae 6 isolated teeth, 5 vertebrae, 2 humeri, 1 ulna, 1 radus, 2 femora, 1 tibia, 2 fibulae and 2 long bone shafts (Filikomys primaevus).

Note: Possibly from Troodon formosus.

 

 

Locality: Glacier County, Montana.

Horizon: Two Medicine Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material:

MOR 748: A partial skeleton of an adult with an egg clutch.

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