Genus: Nanotyrannus BAKKER, WILLIAMS & CURRIE, 1988
Etymology: Greek, nanos “dwarf, pigmy” and Greek, tyrannos, “king”, Pigmy tyrant.
= Chicagotyrannus BAKKER & CURRIE , (nomen nudum)
Etymology: In reference to the Field Museum in Chicago, and Greek, tyrannos “king”.

Note: Note: Clevelanotyrannus was a name in a citation by CURRIE, et al in CURRIE, 1987 (Bakker, R.T., Williams, M., and Currie, P.J. in preparation. The Tyrant Dinosaurs--a redefinition of Tyrannosaurus, Albertosaurus, Gorogsaurus, Daspletosaurus, Tarbosaurus, and a new genus of dwarf tyranosaurine, Clevelanotyrannus; with a discussion of head-neck posture, prey-attacking adaptations and head-butting behavior. Submited to Hunteria. This was later changed when the official paper of Nanotyrannus was published.).

Species: lancensis (GILMORE, 1946) BAKKER, WILLIAMS & CURRIE, 1988
= Gorgosaurus lancensis GILMORE, 1946
Etymology: In reference to the Lance Formation.
= Albertosaurus lancensis (GILMORE, 1946) RUSSELL, 1970
= Albertosaurus (Nanotyrannus) lancensis (GILMORE, 1946)
= Deinodon lancensis (GILMORE, 1946) KUHN, 1965

Holotype: CMNH 7541

Locality: Sand Creek, Carter County, Montana.

Horizon: Lower Hell Creek Formation.

Biostratigraphy:

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

Material: Nearly complete skull and lower jaws in occlusion. The skull is missing the squamosal, postfrontal, quadratojugal, and the upper half of the quadrate of the right side; there is some disarrangement of the bones of the palate, and many of the teeth are either missing or incomplete.

Note: A CAT scan has shown that this specimen is even less complete than originally thought, much is plaster and stone.

Top and middle after Bakker, et al, 1988.

Referred material:

Locality: Corson County, South Dakota.

Horizon: Lance Formation.

Biostratigraphy:

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

Material:

Uncataloged specimens at Denver Museum of Natural History: Three Teeth broken at the crown-root junction.

 

LUPTON, GABRIEL & WEST, 1980

Locality: McCone County, Montana.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

Number: Not given: Five isolated teeth.

 

LANGSTON, 1955, field notes.

Locality: Cochrane Paskapoo, Alberta Province, Canada.

Horizon:

Biostratigraphy:

Age: Late Cretaceous.

Material:

Number: Not given: Skull and Skeleton.

 

LARSON, 1997 (pers. comm.)

Locality: Field Museum "Sue" locality, Maurice Williams’s Ranch, Cheyenne River Indian Reservation, near Faith, Meade County, South Dakota.

Horizon: Hell Creek Formation, about 15 feet above the contact with the Fox Hills Formation.

Biostratigraphy:

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

Material:

BHI: Jugal, 3 teeth.

Possible lachrymal, but may belong to Tyrannosaurus rex.

Note: Found with “Sue”. Once thought to have been a juvenile Tyrannosaurus rex.

 

SNYDER, McLAIN, WOOD & CHADWICK, 2020

Locality: Hanson Ranch (HR), northern Niobrara County, Eastern Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

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

Material:

Number: Not given: 135 teeth.

 

= Nanotyrannus sp SPENCER, TURNER & CHADWICK, 2001

Locality: Niobrara County, Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

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

Material:

Number: Not given: Teeth.

 

STENERSON & O’CONNER, 1994

Locality: Northwestern South Dakota.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

Number: Not given:

 

STEIN, 2021

Locality: Tooth Draw Deposit, Butte County, South Dakota.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

TD-16-033: Rooted right dentary tooth.

TD-13-247: Pre-maxillary tooth.

TD-17-182: Adult right dentary tooth.

TD-12-262: Juvenile right dentary(?) tooth.

Numbers: Not given: 418 teeth, and dozens of unnumbered specimens.

TD-11-121: Manual claw.

 

WROBLEWSKI, 2026

= Aublysodon mirandus WROBLEWSKI,1998

Locality: Western Hanna Basin, Carbon County, South-central Wyoming.

Horizon: Lower Ferris Formation.

Biostratigraphy:

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

Material:

UW 26310, 26285: Maxillary or dentary teeth.

UW 26250: Premaxillary tooth.

 

 

YUN, 2019

Locality: Harding County, South Dakota.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

KPM-NNV00003: tooth.

 

 

ZANNO & NAPOLI, 2025

Locality: Montana.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

KUVP 156375: Partially disarticulated skull and associated postcranial skeleton.

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