Genus: Hadrokkosaurus WELLES 1957
Etymology:
= Taphrognathus WELLES 1947 non BRANSON & MEHL 1941
Etymology:

Species: bradyi (WELLES 1947)
Etymology:
= Taphrognathus bradyi WELLES 1947

Holotype: UCMP 36199

Locality: Geronimo (Holbrook) quarry, quarry, UC V-3922, on Highway 66, 6 miles west of Holbrook, immediately west of Geronimo Trading post, Apache County, Arizona.

Horizon: Holbrook Member, Moenkopi Formation.

Biostratigraphy:

Age: Anisian Stage, Lower Mid Triassic Epoch, Early-Middle Triassic.

Material: Right mandibular ramus lacking only the articular.

Refered material:

UCMP 36200: Anterior extremity of right dentary.

UCMP 36201: Partial right dentary.

UCMP 36202-3: Partial left dentaries.

UCMP 36205: Partial left prearticular.

UCMP 36210: Right angular.
Note: May not be Hadrokkosaurus.

UCMP 36833: Approximately anterior one-third of right lower jaw ramus missing tip of symphysal area.

UCMP 36834: Approximately anterior three-quarters of right dentary.

UCMP 36835: Partial right dentary.

UCMP 36839: ?Right surangular.

UCMP 75434: Anterior extremity of left dentary.
Note: May not be Hadrokkosaurus.

UCMP 152390-1: Fragmentary right and left dentaries.
Note: UCMP 152391 may not be Hadrokkosaurus.