Species: backmani RUSSELL, 1934
Etymology:

Holotype:

Locality:

Horizon:

Biostratigraphy:

Age:

Material:

Referred material:

BYRANT, 1990

Locality: Eastern Montana.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

UCMP 117385: Shell fragments.

 

EBERTH, 1987

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:

Number: Not given:

HOLYROD & HUTCHISON, 2002

Locality: V 86063, western North Dakota.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

172307:

Locality: V 86096, western North Dakota.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

172212:

 

Locality: UCMP V-5819, Niobrara County (Formerly Converse County), Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

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

Material:

54215:

 

Locality: UCMP V65238, Niobrara County, Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

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

Material:

173427: