Genus: Thalassomeodon WELLES, 1943
Etymology: Greek, thalassa, “sea”, and Greek, medon, “lord, ruler”: Sea lord.
= Alzadasaurus WELLES 1943 (partim)
Etymology: In reference to the town of Alzada, Montana, near where the specimen was found, Greek, sauros, “lizard”: Alzada lizard.

Species: haningtoni WELLES, 1943
Etymology:

Referred material:

CARPENTER, 1999

Locality: Seward County, Nebraska.

Horizon: Graneros shale.

Biostratigraphy:

Age: Lower Cenomanian Stage, Upper Middle Gallic Subepoch, Lowermost Gulf Epoch, Middle Cretaceous.

Material:

USNM 50132: Fragmentary specimen.
Note: Cephalopods and gastroliths found in the stomach region (CICIMURRI & EVERHART, 2001).

 


= Alzadasaurus riggsi WELLES, 1943
Etymology:
= Elasmosaurus serpentinus Fide RIGGS, 1939

Holotype: FMNH P 12009

Locality: Alzada, Carter County, Montana.

Horizon: Belle Fourche Formation.

Biostratigraphy:

Age: Early Cenomanian Stage, Uppermiddle Gallic Subepoch, Lowermost Gulf Epoch,, Middle Cretaceous.
Note: Was Benton Formation, Turonian Stage, Uppermost Gallic Subepoch, Lower Gulf Epoch, Late Cretaceous.

Material: 60 or more vertebrae, both scapulae, coracoids, the left paddle almost complete, left pubis, and both ischia and ilia.
Note: 206 granite gastroliths.

_____________________________________________________________________________________
Sp

= Alzadasaurus? DARBY & OJAKANGAS, 1980

Locality: Forsyth, Montana.

Horizon: Bearpaw Formation.

Biostratigraphy:

Age: Upper Campanian-Maastrichtian Stage, Upper Senonian Subepoch, Upper Gulf Epoch, Late Cretaceous.

Material:

Number: Not given: Fragmentary skeleton and gastroliths.