Genus: Tytthostonyx OLSON & PARRIS, 1987
Etymology: Greek, tytthos, "little," and Greek, stonyx, "any sharp point." The name is masculine in gender and refers to the small, presumably rudimentary, ectepicondylar spur. It should not be confused with the coleopteran genus Tytthonyx, based on onyx, claw.

Species: glauconiticus OLSON & PARRIS, 1987
Etymology: From Latin, glaucus (Greek, glaukos), "bluish green or gray, sea-colored," applied to greensands because of their color, although appropriate because of their marine origins as well; in reference to the holotype having been recovered form beds of glauconite.

Holotype: NJSM 11341

Locality: Main fossiliferous layer of the Inversand Company marl pit, Sewell, Gloucester County, New Jersey.

Horizon: Basal Hornerstown Formation, Greensand, Rancocas Group.


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

Material: Right humerus lacking the ventral tubercle, portions of the pectoral crest and other parts of the proximal end.

Note: There is some debate on whether this formation is Maastrichtian, Late Cretaceous or Danian, Early Paleocene.