Species: laevis MARSH, 1889
Etymology:
Holotype: YPM 11780
Locality: Quarry 5 of LULL 1915, Lance Creek area, Wyoming.
Horizon: Lance Formation.
Biostratigraphy:
Age: Lancian age, upper Maastrichtian Stage, uppermost Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.
Material: Fragment of right mandible containing LP2-4 and alveoli of more
mesial teeth.
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Species: praestans MARSH, 1892
Etymology:
Holotype: USNM 2133
Locality: Converse County, Wyoming.
Horizon: Lance Formation.
Biostratigraphy:
Age: Lancian age, upper Maastrichtian Stage, uppermost Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.
Material: Portion of right lower jaw containing 2 molars.
Paratype: USNM 2886: Lower molar.