Pterosaurs represent an unusual group of diverse archosauromorphan vertebrates, characterized by large skulls, light body plans, and extremely elongated arms. Among them, there were the small anurognathids who sported large, wide heads and very long wings; gar-toothed, slender-snouted “rhamphorhynchids” (a likely paraphyletic grade); long-necked, long-snouted, many-toothed ctenochasmatoids; the gigantic pteranodontids and azhdarchids, some sporting extremely large skulls for their size and the latter sporting extremely long necks; anhanguerids, with their keel-snouted jaws and tapejarids with their high, triangular(-ish) crests.
Among the pteranodontids, a peculiar set of skeletons produced a typical Pteranodon-like skull, but with very, very odd bifurcating thin crests. Referred to Nyctosaurus  as based on an unresolved, and possibly unique species, the specimens that comprise this study are currently privately owned. This issue tends to lead to discussions on whether scientists should study or even mention privately-owned material, as well as the wealth of information confined to localized and unseen material held in private hands due to the prestige of collecting, owning, and sometimes even stealing fossils for the sake of notoriety or greed. While not all of these characteristics apply to Bennett’s  specimens (labeled KJ1 and KJ2), they elicit the need to examine ethical practices for scientists who discuss material not available for re-examination in case of need to verify observations (which generally amounts to heresay), as well as private collectors who may spend millions of dollars to acquire a large fossil, often publically, only to then let it disappear, taking with it any potential information it may elide.
In many ways, since their publication, KJ1 and KJ2 have become mastheads in several things, prominent pieces in both the reconstruction of pterosaurs, the aerodynamic options of their cranial shape , and in the collection and reporting of private specimens.
 Bennett, S. C. 2003. New crested specimens of the Late Cretaceous pterosaur Nyctosaurus. Paläontologische Zeitschrift 77:61-75.
 Xing L., Wu J., Lu Y., Lü J.-c. & Ji Q. 2009. Aerodynamic characteristics of the crest with membrane attachment on Cretaceous pterodactyloid Nyctosaurus. Acta Geologica Sinica 83(1):25-32.