they may have had other functions as well. Unlike the earlier pterosaurs, such as the rhamphorhynchids and the pterodactylids, Geosternberigia had a toothless beak that was made of solid, bony margins that projected from the base of the jaws, similar to modern-day birds. The structure of the beaks were long, slender, and ended in thin, sharp points. Its maxilla was also found to be longer than the mandible, and was curved upward. Classification Geosternbergia was traditionally considered a species, or occasionally subgenus, of the similar pterosaur Pteranodon, in most major studies of pteranodontians through the 1990s. However, a 2010 review of the group by A.W.A. Kellner suggested that Pteranodon sternbergi was different enough from P. longiceps to belong in a distinct genus, to which Kellner also referred a new species, Geosternbergia maiseyi. Earlier, pterosaur researcher Chris Bennett had considered the G. maiseyi specimen an adult male P. longiceps. Below is a cladogram showing the phylogenetic placement of this genus within Pteranodontia from Andres and Myers (2013). Paleobiology Sexual variation Adult Geosternbergia specimens may be divided into two distinct size classes, small and large, with the large size class being about one and a half times larger than the small, and the small being twice as common as the large. Both size classes lived alongside each other, and while researchers had previously suggested that they represent different species, Christopher Bennett showed that the differences between them are consistent with the concept that they represent females and males, and that Geosternbergia species were sexually dimorphic. Skulls from the larger size class preserve large, upward and backward pointing crests, while the crests of the smaller size class are small and triangular. 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. The gender of the different size classes was determined, not from the skulls, but from the pelvic bones. Contrary to what may be expected, the smaller size class had disproportionately large and wide-set pelvic bones. Bennett interpreted this as indicating a more spacious birth canal, through which eggs would pass. He concluded that the small size class with small, triangular crests represent females, and the larger, large-crested specimens represent males. Note that the overall size and crest size also corresponds to age. Immature specimens are known from both females and males, and immature males