The first fossils of Pteranodon sternbergi were collected by American paleontologist George F. Sternberg in 1952 from the lower portion of the Niobrara Formation.

The fossils of the animal looked similar to those of the species Pteranodon longiceps, but the crests were set upright and in a slightly different position.

[1] In 1966, American paleontologist John Christian Harksen assigned the specimens found as a new species of Pteranodon called P. sternbergi due to its distinct upright crest that set it apart from P. longiceps.

P. sternbergi was assigned to this subgenus along with another species called P. walkeri, but Miller then found out that the name Sternbergia had been preoccupied, so he changed it into Geosternbergia instead.

[3] The most complete example of the species, currently in the collections of the University of Alberta Laboratory for Vertebrate Paleontology as specimen number UALVP 24238, is a partially-articulated sub-adult fossil with a wingspan of about 4 meters (13 ft).

The fossil was found by Richard C. Fox and Allen Lindoe in rocks belonging to the lower part of the Smoky Hill Chalk Member of the Niobrara Formation.

However, a re-examination of the fossil published in 2017 by Elizabeth Martin-Silverstone and colleagues argued that the differences in the snout were more likely due to male pteranodontids having longer, broader bills than the more complete female specimens Kellner used for comparison.

Geosternbergia existed as a group for more than four million years during the late Coniacian – early Campanian stages of the Cretaceous period.

[3] The genus is present in the lower the Niobrarra Formation except for the upper two; in 2003, Kenneth Carpenter surveyed the distribution and dating of fossils in this formation, demonstrating that Pteranodon sternbergi existed there from 88 to 85 million years ago, while the species later named G. maiseyi existed between 81.5 and 80.5 million years ago.

P. sternbergi differs from its close relative Pteranodon longiceps mainly due to its earlier time period and broader, more upright crest.

[8] Unlike the earlier pterosaurs, such as the rhamphorhynchids and the pterodactylids, P. sternbergi had a toothless beak that was made of solid, bony margins that projected from the base of the jaws, similar to modern-day birds.

Some larger skulls also show evidence of a second crest that extended long and low, toward the tip of the beak, which is not seen in smaller specimens.