Species: hexagonus COPE, 1887 (nomen vanum)
Etymology:

Holotype: AMNH 5691

Locality: Unknown, San Juan Basin, New Mexico.

Horizon: "Fox Hills Cretaceous", Lewis shale and/or Pictured Cliffs Sandstone.

Biostratigraphy:

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

Material: Cervical centrum and isolated limb bones, probably of a juvenile elasmosaurid.
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Species: megaloporus COPE, 1887 (nomen vanum)
Etymology:

Holotype: AMNH 5690

Locality: Unknown, San Juan Basin, New Mexico.

Horizon: "Fox Hills Cretaceous", Lewis shale and/or Pictured Cliffs Sandstone.

Biostratigraphy:

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

Material: 5 cervical centra and limb bone fragments of a juvenile elasmosaurid?
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Species: microporus COPE, 1887 (nomen vanum)
Etymology:

Holotype:

Locality: Unknown, San Juan Basin, New Mexico.

Horizon: "Fox Hills Cretaceous", Lewis shale and/or Pictured Cliffs Sandstone.

Biostratigraphy:

Age: Upper Campanian Stage, Senonian Substage, Upper Gulf Epoch, Late Cretaceous.

Material: Cervical centra.