FHSM 17956 (Bennett 2017, see below) was considered the smallest known Pteranodon. It is half the size of the similarly gracile Triebold specimen, Pteranodon NMC41-358. and similar in size to Ptweety, a more completely known juvenile now lost to science. Contra Bennett 2017, the extensor tendon process is strongly connected if not fused (the surface was prepared away), as in all Pteranodon specimens. Contra Bennett, Ptweety exhibits traits of Pteranodon, not Nyctosaurus. Contra Bennett, some wrist bones were originally misidentified (see above) after taphonomic crushing and breakage.

'Ptweety' private collection (undescribed) appears to be a small Nyctosaurus based on the scapulae and other proportional traits. This specimen, originally described as a Pteranodon juvenile was discovered by Kenneth Jenkins, a Kansas collector responsible for finding the KJ specimens of the crested Nyctosaurus and the largest Pteranodon skull. Earlier errors are corrected here.

Bennett (1991, 1992, 1994, 2001) thoroughly described Pteranodon, but proposed that only two species were present, P. longiceps and P. sternbergi, with all other variations attributable to gender (small crest, large pelvis) and maturity (small crest, small size, unfused scapulocoracoid, unfused extensor tendon process). Bennett did not publish a cladistic analysis to support his hypothesis, which has been widely accepted. Here a phylogenetic analysis of pterosaurs reveals that these differences were actually phylogenetic, with most (but not all) smaller Pteranodon with smaller crests were more primitive, closer to Eopteranodon and Germanodactylus. The juvenile, Ptweety, demonstrates that the rostrum was not shorter and the orbit was not larger in juveniles. Embryos of Pterodaustro and a basal ornithocheirid also demonstrate this. Ptweety the juvenile also had a fused extensor tendon process.

The family tree of Pteranodon is here. The family tree of the Ornithocephalia and Germanodactylia is here. The expanded family tree of the Pterosauria is here.