How Big, Could They Fly?
Giant birds of prey, the Argentinian Teratorn (argentavis magnificens), as large as a man weighing 170 - 200 lbs but with wingspans of over twenty-five feet and individual wing feather lengths as long as five feet, flew within recorded history. A twenty-five foot plus wing size would limit such a bird to more open areas such as the South American pampas or the North American great plains --- i.e., Thunderbirds --- as maneuverability around trees and shrubs would seem difficult. Feather size is estimated to have been 1.5 meters long (60 inches); and 20 centimeters wide (8 inches), similar in size to the feather from the desert southwest described in The Boy and the Giant Feather. It is not presently known if this Teratorn actively flew by flapping its wings or if it mostly soared as do present-day condors. See Evidence of the Giant Birds.
No strong proof or confirming evidence indicates anything much larger than 30 lbs or so flies anymore, and those creatures that do, albatrosses and a few of the largest condors and eagles, are marginal. No known present day flying creature has EVOLVED into anything like former sizes, and the one or two birds which have retained huge sizes have forfeited any ability of flight, their wings becoming vestigial.
A book of interest is Adrian Desmond's "The Hot Blooded Dinosaurs." Desmond has a good deal to say about the pteranodon, the 40 - 50 lb pterosaur which scientists used to believe was the largest creature which ever flew:
"Pteranodon had lost its teeth, tail and some flight musculature, and its rear legs had become spindly. It was, however, in the actual bones that the greatest reduction of weight was achieved. The wing bones, backbone and hind limbs were tubular, like the supporting struts of an aircraft, which allows for strength yet cuts down on weight. In Pteranodon these bones, although up to an inch in diameter, were no more than cylindrical air spaces bounded by an outer bony casing no thicker than a piece of card. Barnum Brown of the American Museum reported an armbone fragment of an unknown species of pterosaur from the Upper Cretaceous of Texas in which 'the culmination of the pterosaur... the acme of light construction' was achieved. Here, the trend had continued so far that the bone wall of the cylinder was an unbelievable one-fiftieth of an inch thick Inside the tubes bony crosswise struts no thicker than pins helped to strengthen the structure, another innovation in aircraft design anticipated by the Mezosozoic pterosaurs."
"The combination of great size and negligible weight must necessarily have resulted in some fragility. It is easy to imagine that the paper-thin tubular bones supporting the gigantic wings would have made landing dangerous. How could the creature have alighted without shattering all of its bones? How could it have taken off in the first place? It was obviously unable to flap twelve-foot wings strung between straw-thin tubes. Many larger birds have to achieve a certain speed by running and flapping before they can take off and others have to produce a wing beat speed approaching hovering in order to rise. To achieve hovering with a twenty-three foot wingspread, Pteranodon would have required 220 lbs of flight muscles as efficient as those in humming birds. But it had reduced its musculature to about 8 lbs, so it is inconceivable that Pteranodon could have taken off actively."
"Pteranodon, then, was not a flapping creature, it had neither the muscles nor the resistance to the resulting stress. Its long, thin albatross-like wings betray it as a glider, the most advanced glider the animal kingdom has produced. With a weight of only 40 lbs the wing loading was only one pound per square foot. This gave it a slower sinking speed than even a man-made glider, where the wings have to sustain a weight of at least 4 lbs per square foot. The ratio of wing area to total weight in Pteranodon is only surpassed in some of the insects. Pteranodon was constructed as a glider, with the breastbone, shoulder girdle and backbone welded into a box-like rigid fuselage, able to absorb the strain from the giant wings. The low weight combined with an enormous wing span meant that Pteranodon could glide at ultra-low speeds without fear of stalling. Cherrie Bramwell of Reading University has calculated that it could remain aloft at only 15 m.p.h. So take-off would have been relatively easy. All Pteranodon needed was a breeze of 15 m.p.h. when it would face the wind, stretch its wings and be lifted into the air like a piece of paper. No effort at all would have been required. Again, if it was forced to land on the sea, it had only to extend its wings to catch the wind in order to raise itself gently out of the water. It seems strange that an animal that had gone to such great lengths to reduce its weight to a minimum should have evolved an elongated bony crest on its skull."
Desmond has mentioned some of the problems which even the pteranodon faced at fifty lbs or so; no possibility of flapping the wings for instance. The giant Teratorn finds of Argentina were NOT known when the book was written... they came out in the eighties in issues of Science Magazine and other places. The Teratorn was a 160 - 200 lb eagle or condor like creature with a wingspan of over twenty-five feet, a modern bird whose existence involved flapping wings, aerial maneuver etc. How so? There are a couple of other problems which Desmond does not mention, including the fact that life for a pure glider would be almost impossible in the real world, and that some limited flying ability would be necessary for any aerial creature. Living totally at the mercy of the winds, a creature might never get back home to its nest and children given the first contrary wind.
There is one other problem. Desmond notes a fairly reasonably modus operandi for the pteranodon, i.e. that it had a throat pouch like a pelican, has been found with fish fossils indicating a pelican-like existence, soaring over the waves and snapping up fish without landing. That should indicate that, peculiarly amongst all of the creatures of the earth, the pteranodon should have been practically IMMUNE from the great extinctions of past ages as oceans were always there and fish always there.
Back to Adrian Desmond for more on size as related to pterosaurs:
"It would be a grave understatement to say that, as a flying creature, Pteranodon was large. Indeed, there were sound reasons for believing that it was the largest animal that ever could become airborne. With each increase in size, and therefore also weight, a flying animal needs a concomitant increase in power (to beat the wings in a flapper and to hold and manoeuvre them in a glider), but power is supplied by muscles which themselves add still more weight to the structure."
"The larger a flyer becomes the disproportionately weightier it grows by the addition of its own power supply. There comes a point when the weight is just too great to permit the machine to remain airborne. Calculations bearing on size and power suggested that the maximum weight that a flying vertebrate can attain is about 50 lbs: Pteranodon and its slightly larger but lesser known Jordanian ally Titanopteryx were therefore thought to be the largest flying animals."
Notice that the calculations mentioned say about 50 pounds is max for either a flier or a glider, and that experience from our present world absolutely coincides with this and, in fact, don't go quite that high; the biggest flying creatures which we actually see are albatrosses, geese etc. at around 30 - 35 pounds.
But in 1972 the first of a spectacular series of finds suggested that we must drastically rethink our ideas on the maximum size permissible in flying vertebrates. In the summer a then graduate student in Geological Sciences at the University of Texas, Douglas A. Lawson, made a discovery in Big Bend National Park that electrified scientists and non-scientists alike. What Lawson found were the fragmentary fossilized remains of a wing belonging to the largest of all flying creatures. After removing the broken and fragile pieces from the sandstone that surrounded them, about 200 fragments of petrified bone, ranging in size from that of a fist to that of a postage stamp were tediously fitted back together by the staff at the Texas Memorial Museum's Vertebrate Paleontology Laboratory. By 1975, studies of the specimen by Lawson and his supervisor, Wann Langston, Jr. Had determined that the animal, a 65 million year old pterodactyl from the Age of Dinosaurs, had a wing spread of over 40 feet, greater than a 4-place Cessna airplane or an F-18 fighter. It was about twice as large as the biggest pterodactyl known up to that time. Interestingly, Lawson found the remains in deposits that were non-marine; the ancient entombing sediments are thought to have been made instead by floodplain silting. The immense size of the Big Bend pterosaurs, offically named Quetzalcoatlus northropi, but known affectionately in the palaeontological world as '747s' or 'Jumbos', may be gauged by setting one of the Texas upper arm bones alongside that of a Pteranodon: the 'Jumbo' humerus is fully twice the length of Pteranodon's. Lawson's computer estimated wingspan for this living glider is over fifty feet It is no surprise, says Lawson announcing the animal in Science in 1975, that the definitive remains of this creature were found in Texas.
Unlike Pteranodon, these creatures were found in rocks that were formed 250 miles inland of the Cretaceous coastline. The lack of even lake deposits in the vicinity militates against these particular pterosaurs having been fishers. Lawson suggests that they were carrion feeders, gorging themselves on the rotting mounds of flesh left after the dismembering of a dinosaur carcass. Perhaps, like vultures and condors, these pterosaurs hung in the air over the corpse waiting their turn. Having alighted on the carcass, their toothless beaks would have restricted them to feeding upon the soft, pulpy internal organs. How they could have taken to the air after gorging themselves is something of a puzzle. Wings of such an extraordinary size could not have been flapped when the animal was grounded. Since the pterosaurs were unable to run in order to launch themselves they must have taken off vertically. Pigeons are only able to take-off vertically by reclining their bodies and clapping the wings in front of them; as flappers, the Texas pterosaurs would have needed very tall stilt-like legs to raise the body enough to allow each of the 24-foot wings to clear the ground The main objection, however, still rests in the lack of adequate musculature for such an operation. Is the only solution to suppose that, with wings fully extended and elevators raised, they were lifted passively off the ground by the wind? If Lawson is correct and the Texas pterosaurs were carrion feeders another problem is envisaged. Dinosaur carcasses imply the presence of dinosaurs. The ungainly Brobdignagian pterosaurs were vulnerable to attack when grounded, so how did they escape the formidable dinosaurs? Left at the mercy of wind currents, take-off would have been a chancy business. Lawson's exotic pterosaurs raise some intriguing questions. Only continued research will provide the answers.
Note that Desmond mentions a number of ancillary problems, any of which would throw doubt on the pterosaur's ability to exist as mentioned, and neglects the biggest question of all: the calculations which say 50 lbs are max have not been shown to be in error; we have simply discovered larger creatures. Much larger. This is what is called a dilemma.
Now we come to what Robert T. Bakker has to say about the Texas Pterosaurs ("The Dinosaur heresies", Zebra Books, pp 290-291:
"Immediately after their paper came out in Science, Wann Langston and his students were attacked by aeronautical engineers who simply could not believe that the big Bend dragon had a wingspan of forty feet or more. Such dimensions broke all the rules of flight engineering; a creature that large would have broken its arm bones if it tried to fly... Under this hail of disbelief, Langston and his crew backed off somewhat. Since the complete wing bones hadn't been discovered, it was possible to reconstruct the Big Bend Pterodactyl [pterosaur] with wings much shorter than fifty feet."
The original reconstruction had put wingspan for the pterosaur at over 60'. Bakker goes on to say that he believes the pterosaurs really were that big and that they simply flew despite our not comprehending how, i.e. that the problem is ours. He does not give a solution as to what we're looking at the wrong way.
So much for the idea of anything RE-EVOLVING into the sizes of the flying creatures of the past. What about the possibility of man BREEDING something like a pteratorn? Could man actively breed even a 50 lb eagle?
David Bruce's "Bird of Jove", Ballentine Books, 1971, describes the adventures of Sam Barnes, one of England's top falconers at the time, who actually brought a Berkut eagle out of Kirghiz country to his home in Pwllheli, Wales. Berkuts are the biggest eagles, and Atlanta, the particular eagle which Barnes brought back, at 26 lbs in flying trim, is believed to be as large as they ever get. These, as Khan Chalsan explained to Barnes, have been bred specifically for size and ferocity for many centuries. They are the most prized of all possessions amongst nomads, and are the imperial hunting bird of the turko-mongol peoples.
The eagle Barnes brought back had a disease for which no cure was available in Kirghiz, and was near to death then, otherwise there would have been no question of his having her. Chalsan explained that a Berkut of Atlanta's size would normally be worth more than a dozen of the most beautiful women in his country.
The killing powers of a big eagle are out of proportion to its size. Berkuts are normally flown at wolves, deer, and other large prey. Barnes witnessed Atlanta killing a deer in Kirghiz, and Chalsan told him of her killing a black wolf a season earlier. Mongols and other nomads raise sheep and goats, and obviously have no love for wolves. A wolf might be little more than a day at the office for Atlanta with her eleven-inch talons, however, a wolf is a major-league deal for an average sized Berkut at 15 - 20 lbs. Chalsan explained that wolves occasionally win these battles, and that he had once seen a wolf kill three of the birds before the fourth killed him. Quite obviously, there would be an advantage to having the birds be bigger, i.e. to having the average berkut be 25 lbs, and a big one be 40 or 50.
It has never been done, however, despite all of the efforts since the days of Ghengis Khan. We have Ghengis Khan's famous "What is best in life..." quote, and the typical mongol reply from one of his captains involved falconry. They regarded it as important. Ghengis Khan, Oktai, Kuyuk, Hulagu, Batui, Monke, Kubilai et. al. were all into this sport big time, they all wanted these birds big, since they flew them at everything from wolves and deer (a big berkut like Atlanta can drive its talons in around a wolf's spine and snap it) to leopards and tigers, and there was no lack of funds for the breeding program involved. Ghengis Khan did not suffer from poverty.
Marco Polo tells how he heard of a mighty feather presented to the Grand Khan of China purportedly taken from a Rukh and measuring nine "spans" long. In classic literature a "span" is usually described as being the distance between the tip of the thumb and the tip of the little finger in a spread out hand, roughly nine inches. That would make the feather somewhere just over six feet long, similar in length to the one described as coming from the American southwest in The Boy and the Giant Feather link cited below.
From THE PIASA MONSTER BIRD
Moreover, the breeding of berkuts has continued apace from that day to this, including a 200 year stretch during which those people ruled almost all of the world which you'd care to own at the time, and they never got them any bigger than 25 lbs or so.
Remember Desmond's words regarding the difficulty which increasingly larger birds will experience getting airborne from flat ground? Atlanta was powerful enough in flight, but she was not easily able to take off from flat ground. Barnes noted one instance in which a town crank attacked Atlanta with a cane and the great bird had to frantically run until it found a sand dune from which to launch herself. This could mean disaster in the wild. A bird of prey will often come to ground with prey, and if she can't take off from flat ground to avoid trouble once in awhile... it would only take once. Khan Chalsan had explained the necessity of having the birds in captivity for certain periods, and nesting wild at other times. A bird bigger than Atlanta would not survive the other times.
Leonardo Da Vinci's flying machine from the 1500s
THE ABOVE GRAPHIC FROM:
DA VINCI: Did He Fly?
The 170-200 pound Teratorns were able to fly...did Leonardo Da Vinci?
THE VULTURE AS TOTEM
QUETZALCOATLUS: Dragon of the Clouds
MEDITATION ALONG METEOR CRATER RIM
POWER OF THE SHAMAN: Where Does It Come From, How Does It Work?
Where Is It Now, What Happened To It?
The above article, although edited and culled from a number of sources for our purposes here, is based on previous works attributed to:
Ted Holden (B. A., Mathematics, Old Dominion University, Virginia; M. A., Mathematics, Chapel Hill University), a contributor to computer journals, has been published in Fantek Gateways and currently studying Russian. The orginal page no longer calls up. Try: http://www.bearfabrique.org/.