The Magical, Mystery Pterosaur

Nyctosaurus gracilis

Written & illustratedby Gregory S. Paul

not be embarrassed by the results. The crest is so extreme in size and formthat it is difficult to believe real, live creatures could have lived with such astructure, especially fliers.

Known from the sediments laid down in the famed Niobrara inte-rior seaway that covered what are now the great plains, Nyctosaurus andPteranodon were entirely marine in habits so restorations Showing eithersoaring over the heads of tyrannosaurs are wrong, wrong, wrong. It is asabsurd as showing an albatross over an elephant. Showing these pterosaursassociated with Tyrannosaurus rex is doubly inappropriate because bothappear to have been extinct by the Maastrichtian. So it is equivalent to show-ing a Miocene pseudodontorn over a living elephant. The classic remains ofthese pterosaurs come from the sediments lain down by the famed Niobraraseaway when it cut the continent in two from Texas to the Yukon. They mayhave soared over the oceans of the world, back when most of the deep seaconsisted of the superPacific. They probably spent much of their lives in theair, bobbing about on the surface to rest Of perhaps feed, and returning toland only to breed.

It is generally thought that the Nyctosaurus and Pteranodon weresea wave soarers in a manner similar toalbatross and other long winged marinebirds. As I explain in Dinosaurs of theAir and elsewhere, past estimates of themass of giant pterosaurs have tended tobe way understated, but even whenhefted up to correct values thesepterosaurs were somewhat more lightlyloaded than marine birds. A-;nyctosaurweighed just a couple of pounds.Despite their very long span, albatrosswings are actually rather heavily loadedin terms of mass/wing area because thewings are so narrow and the body quitelarge. The flight of the lighterpterosaurs must have been somewhatdifferent from that of albatross, andmay have been more like that of simi-larly lightly loaded frigate birds. Butadding to the perplexity of Nyctosaurusand Pteranodon flight are the very largepectoralis crests on the humeri, sug-gesting they had larger, higher leverageflight muscles than soaring birds inwhich the crest is very reduced.Perhaps the pterosaurs flapped moreoften than their modem counterparts.Even better adapted for flapping werethe, in some cases even more titanic,nonmarine azhdarchids includingQuetzalcoatlus, in which the wingswere relatively shorter and much morerobustly constructed even in smallerexamples.

Bennett notes critical points aboutnyctosaur crests in regards to their pos-sible impact on flight. First, their Cl1SP

edges differ from the amorphous rimsof the crests of pterosaurs in which ker-

atin sheaths greatly expand the area of the crest. So in life the crest proba-bly looked pretty much like what we see in the fossils, being reminiscent offlattened deer antlers. If so, then the crest would have had minimal ruddereffect for something of its great dimensions. Second, there are specimensabout as big as the crested skeletons that lack large crests. That the crestlessspecimens are consistently immature in their bone structure indicates thatthe crests did not appear until final maturity. It is less likely that the crest-less specimens were the girls and the crested ones the boys, although thiscannot be ruled out until more specimens are sampled. If remains quite pos-sible that, as in Pteranodon, the crests of females were much smaller than

© Gregory S PaulJust when one thinks that fossil

creatures cannot get any wilder orwackier, along comes another beast ofancient days that blows our neural net-works. And in this case it is not even anew species.

The Late Cretaceouspterosaur Nyctosaurus gracilis wasdiscovered in the late l800s, at prettymuch the same time and place as itslarger and similar relation,Pteranodon. Long known from nearlycomplete skulls and skeletons,Nyctosaurus appeared to lack much inthe way of a head crest. Although its6-9 ft wingspan is impressive by mod-em standards, by late Mesozoic crite-ria it was dwarfed by other pterosaurs,so unadorned Nyctosaurus was prettymuch neglected by paleoartists.

The situation has changeddramatically with the description byChristopher Bennett inPalaontologische Zeitschrift of newspecimens which, unfortunately,reside in private hands. Both fossilsinclude skull and skeletal material.The main body of the skull is notremarkable, being quite similar in out-line' to Pteranodon except that thevery slender upper and lower beak tipsmatched one another in length, unlikethe other pterosaur whose upper beakstrongly overbit the lower. One of thenew Nyctosaurus skulls is pretty muchcompletely preserved, including hap-pily the entire crest. In the other spec-imen the crest is shattered and frag-mentary but what is present shows similar form. The crest consists of aswept back, transversely flattened, very narrow strap that is about two anda half times longer than the skull proper. There is a slight taper progressingup the crest. Shortly up the crest is a branch directed backwards, about thesame length as the skull, and similar in width and breadth to the main branchwi th a slight distal taper.

The crest is a psychedelic structure that gives new meaning to theneocreationist concept of "intelligent" design -- it looks like someonedesigned it while on LSD, A cross between a reindeer and a flying archosauris suggested. Only bioevolution could come up with something like this and

46 Prehistoric Times No, 62 • OCT/NOV 2003

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rather like the tails of peacocks. The bigger and better formed the crest thebetter, being evidence of the health and fitness of the male. The crests couldhave been a solid colored or banded, dark, light or both. Brilliant colors area real possibility. What motions the crest may have been put through areuncertain, vertical and/or broadside presentations are possible. The promi-nent beaks may also have been part of the display, both visually and as ameans to an auditory component via clattering.

The Nyctosaurus scene shows a crowded, guano contaminatedrookery, atop a cliff on a Niobrara island. It is the beginning of the breedingseason, and in the forefront a full crested male and female are displaying toone another in a selection and bonding ritual that another male is approach-ing to try his luck. Other Nyctosaurus rest as still others soar on the cliffinduced updraft, and more fly to and from sea amidst small marine birds.Large marine birds are often mate loyal over long periods of time; we have

..------------------------------------, no idea if this was true of their© Gregory S Paul pterosaurian counterparts. Big

\

marine birds tend to have longlifespans so they breed slowly.

.. The same may have been true

of oceanic pterosaurs. Marinefliers are not well suited 'forgathering much in the way ofnesting materials, which maynot be available on barrenislands anyway.

After pterosaur eggswere deposited they could notbe left exposed to the ele-ments, so the eggs were proba-bly incubated. Adultpterosaurs probably had thehigh metabolic rates needed towarm eggs. Heat transfercould have been via a nakedbrooding patch on the chest, assometimes practiced by birds.Presumably the chicks werefed for a period by one or moreparents. The variable size of

specimens found far out into marine sediments suggest that the pterosaursleft the nest and became active fliers before completing growth, a major dif-ference from most, but not all, birds.

those of the males.The combination of low surface area and failure to appear until all

grown up suggest that the crests were not airfoils such as rudders, but wereinstead display features. In this case a primary objective of the crests wouldbe to have minimal impact upon the aerodynamics of their owners, achievedby being extremely thin from side to side. They probably barely disturbedthe air as they cut .through it like a hot razor through creamy butter.Suggestions that the crests were broad surfaced thrust generating sails (aswhen a wind vessel sails into the wind using the sail to generate lateral liftas the wind blows along its surface) are not viable because, aside from thelack of anatomical evidence, sails only work when the mainbody of the ves-sel has a substrate that it can work against. Water in the case of sail boatsand ships, the ground or ice in case of sail????? [what are terms for sail dri-ven ice runners and land racers"], Also, when sailing against the wind thesail is set at an angle to thedirection of travel, so apterosaur that tried to do thiswith its crest would also haveto swivel its large beak to the \side, creating a rudder effectthat would prevent the crea-ture from moving in astraight line.

One knownpterosaur .exhibits the knifelike lower beak needed tosurface skim for food likeskimmers, but the Niobrarapterosaurs lacked this hydro-dynamic feature. BecausePteranodon's upper beak waslonger than the other, Bennettsuggests it could not feed onthe wing, and instead did sowhile. floating as do somemarine birds such as alba-tross. Surface feeders wouldseem vulnerable to swim-ming predators, perhaps the ~......,=;;.;.;...."""'==-"'--.;;..;;..===later prefer to focus on fat and oil laden fish and cephalopods rather thanskin and bones fliers during joint feeding frenzies. Nyctosaurus may havesurface fed, or dipped into the water while flying like gulls, or both.Preserved soft tissues show a small pouch slung under the incut portion ofthe lower jaw in some small pterosaurs; presumably this was also true of thegiants. The pouch could be used to store fish quickly gathered up duringfeeding frenzies.

Marine pterosaurs had to return to land to reproduce. Being veryvulnerable to land predators, marine pterosaurs probably did so on islands,or at least up in trees or on cliffs inaccessible to predators. There is e idencefor islands in the Niobrara seaway. The concentration of animals from largeareas of ocean into a few breeding spots leads to dense populations, andpterosaur rookeries may have been polluted with massive whitish guanodeposits.

The legs of big marine pterosaurs tend to be reduced both relative(0 the wings and body, suggested they were not very well adapted forground locomotion in the manner also typical of big marine birds. The con-tinental azhdarchids had much longer legs. Nyctosaurus has exceptionallyreduced legs. It also lacked the separate clawed fingers that other pterosaursprobably used for quadrupedal locomotion, and the folded arms were toolong to be easily used in cooperation with the legs. Nyctosaurus may haveclumsily walked on two legs, its short tailed body awkwardly erect, like apterosaurian cross between a "gooney bird" albatross and a penguin. Whenstanding, the arms may have been used as props. Landings after months atsea could have been belly flopping affairs. Takeoffs may have required arunning start unless the wind was up.

Presumably Niobrara pterosaur crests were used as a prominentvisual display to intimidate rivals, and/or impress potential female mates,

Prehistoric Times No. 62 • OCT/NOV 2003