Genus: Haptosphenus ESTES, 1964
Etymology: Greek, hapto, "join or fasten" and Greek, sphenos, "wedge." Referring to the fused splenial.

Species: placodon ESTES, 1964
Etymology: Greek, plakos, "wide" and Greek, odontos, "tooth." Referring to the teeth.

Holotype: UCMP 46035

Locality: UCMP V-5620, Lull Quarry, near the head of a tributary of Buck Creek, Powder River Basin, Niobrara County (Formerly Converse County), Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

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

Material: Almost complete right dentary.

Referred material:

UCMP 49946: Posterior fragment of left dentary, with attached coronoid and part of surangular.

UCMP 49947: Posterior fragment of left dentary.

UCMP 49949: Right dentary, broken posteriorly.

UCMP 49950: Anterior half of right dentary.

UCMP 50031: Right dentary, broken posteriorly.

 

Locality: UCMP V-5711, Bushy Tailed Blowout, Quarry area includes the floor of a small blowout approximately 10 yards northwest of the highest point on the ridge forming the northeastern side of the blowouts of loc. V-5003, S 1/2, Sec. 20, T37N, R64W, Lance Creek, Powder River Basin, Niobrara County, Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

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

Material:

UCMP 49844: Anterior half of right dentary.

UCMP 49845: Left dentary.

UCMP 49846: Anterior half of right dentary.

UCMP 54209: Left dentary, broken posteriorly.

UCMP 54201: Right dentary, broken posteriorly.

 

Unnumbered specimens are present from UC localities V-5815 and V-5817.

Locality: UCMP V-5815, Hatcher Number 2, western side of a cross-stratified sandstone erosional remnant near the center of a large blowout on the crest of a ridge, the distance form the nearest point on the road, approximately 150 yards south of the quarry, to the Johnson ranch is 0.4 miles, Niobrara County (Formerly Converse County), Eastern Wyoming.

Locality: UCMP V-5817, False Disciple Point, cross-stratified sandstone and sandy shales cropping out on the top of the northern end of a long, northwestward-trending ridge that extends from the crest of the divide between the Hancock and Lance Creek drainages, Niobrara County (Formerly Converse County), Wyoming.

 

BRYANT, 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 130698: Maxilla.

UCMP 130735: Dentaries.

 

ESTES, BERBERIAN & MESZOELY, 1969

Locality: Bug Creek Anthills locality, McCone County, Montana.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

MCZ 3686: Fused right dentary and splenial and a coraconid with adhering parts of fused dentary and surangular are preserved.

 

GAO & FOX, 1996

Locality: Gryde Locality, Frenchman River Valley, Southwestern Saskatchewan Province, Canada.

Horizon: Frenchman Formation.

Biostratigraphy:

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

Material:

SMNHP1920.23: Left mandible.

 

Locality: Wounded Knee Locality, Frenchman River Valley, Southwestern Saskatchewan Province, Canada.

Horizon: Frenchman Formation.

Biostratigraphy:

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

Material:

UALVP 29771, 29780: Incomplete mandible.

 

Locality: KUA-1, Stettler County, Alberta Province, Canada.

Horizon: Scollard Formation, Uppermost Edmonton Group.

Biostratigraphy:

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

Material:

UALVP 22921: Incomplete mandible.