348 lines
18 KiB
Plaintext
348 lines
18 KiB
Plaintext
From: news@fedfil.UUCP (news)
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Newsgroups: talk.origins
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Subject: Prehistoric flying creatures and gravity
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Message-ID: <127@fedfil.UUCP>
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Date: 28 Nov 92 05:05:12 GMT
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Organization: HTE
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Lines: 340
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For the benefit of newcomers:
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............................................................
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In the antediluvian world, 350 lb flying creatures soared in skys which
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no longer permit flying creatures above 30 lbs or so. Modern raptors
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(the teratorn) weighing 170 - 200 lbs with wingspans of 30' also flew;
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within recorded history, central asians have been trying to breed hunting
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eagles for size and strength, and have not gotten them beyond 25 lbs or
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thereabouts. At that point they are able to take off only with the greatest
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difficulty. Something was vastly different in the pre-flood world.
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Nothing much larger
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than 30 lbs or so flies anymore, and those creatures, albatrosses and a
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few of the largest condors and eagles, are marginal. Albatrosses in
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particular are called "goonie birds" by sailors because of the
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extreme difficulty they experience taking off and landing, their
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landings being (badly) controlled crashes, and all of this despite long
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wings made for maximum lift.
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The felt effect of the force of gravity on
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earth was much less in remote times, and only this allowed such giant
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creatures to fly. No flying creature has since RE-EVOLVED into anything
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like former sizes, and the one or two birds which have retained such
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sizes have forfeited any thought of flight, their wings becoming
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vestigial.
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A book which I've mentioned a couple of times here is Adrian
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Desmond's "The Hot Blooded Dinosaurs.
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Desmond has a good deal to say about the pteranodon, the 40 - 50 lb
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pterosaur which scientists used to believe to be the largest
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creature which ever flew:
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Pteranodon had lost its teeth, tail and some flight
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musculature, and its rear legs had become spindly. It was,
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however, in the actual bones that the greatest reduction of
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weight was achieved. The wing bones, backbone and hind limbs
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were tubular, like the supporting struts of an aircraft, which
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allows for strength yet cuts down on weight. In Pteranodon
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these bones, although up to an inch in diameter, were no more
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than cylindrical air spaces bounded by an outer bony casing no
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thicker than a piece of card. Barnum Brown of the American
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Museum reported an armbone fragment of an unknown species of
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pterosaur from the Upper Cretaceous of Texas in which 'the
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culmination of the pterosaur... the acme of light
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construction' was achieved. Here, the trend had continued so
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far that the bone wall of the cylinder was an unbelievable
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one-fiftieth of an inch thick! Inside the tubes bony
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crosswise struts no thicker than pins helped to strengthen the
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structure, another innovation in aircraft design anticipated
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by the Mezosozoic pterosaurs.
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The combination of great size and negligible weight must
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necessarily have resulted in some fragility. It is easy to
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imagine that the paper-thin tubular bones supporting the
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gigantic wings would have made landing dangerous. How could
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the creature have alighted without shattering all of its
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bones! How could it have taken off in the first place! It was
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obviously unable to flap twelve-foot wings strung between
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straw-thin tubes. Many larger birds have to achieve a certain
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speed by running and flapping before they can take off and
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others have to produce a wing beat speed approaching hovering
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in order to rise. To achieve hovering with a twenty-three
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foot wingspread, Pteranodon would have required 220 lbs of
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flight muscles as efficient as those in humming birds. But it
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had reduced its musculature to about 8 lbs, so it is
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inconceivable that Pteranodon could have taken off actively.
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Pteranodon, then, was not a flapping creature, it had neither
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the muscles nor the resistance to the resulting stress. Its
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long, thin albatross-like wings betray it as a glider, the
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most advanced glider the animal kingdom has produced. With a
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weight of only 40 lbs the wing loading was only I lb per
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square foot. This gave it a slower sinking speed than even a
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man-made glider, where the wings have to sustain a weight of
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at least 4 lbs per square foot. The ratio of wing area to
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total weight in Pteranodon is only surpassed in some of the
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insects. Pteranodon was constructed as a glider, with the
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breastbone, shoulder girdle and backbone welded into a
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box-like rigid fuselage, able to absorb the strain from the
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giant wings. The low weight combined with an enormous wing
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span meant that Pteranodon could glide at ultra-low speeds
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without fear of stalling. Cherrie Bramwell of Reading
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University has calculated that it could remain aloft at only
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15 m.p.h. So take-off would have been relatively easy. All
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Pteranodon needed was a breeze of 15 m.p.h. when it would face
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the wind, stretch its wings and be lifted into the air like
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a piece of paper. No effort at all would have been required.
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Again, if it was forced to land on the sea, it had only to
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extend its wings to catch the wind in order to raise itself
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gently out of the water. It seems strange that an animal that
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had gone to such great lengths to reduce its weight to a
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minimum should have evolved an elongated bony crest on its
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skull.
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Desmond has mentioned some of the problems which even the
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pteranodon faced at fifty lbs or so; no possibility of flapping
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the wings for instance. The giant PTEROTORN finds of Argentina
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were not known when the book was written... they came out in the
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eighties in issues of Science Magazine and other places. The
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Pterotorn was a 160 - 200 lb eagle with a 27' wingspan, a modern
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bird whose existence involved flapping wings, aerial maneuver etc.
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How so? There are a couple of other problems which Desmond does
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not mention, including the fact that life for a pure glider would
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be almost impossible in the real world, and that some limited
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flying ability would be necessary for any aerial creature. Living
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totally at the mercy of the winds, a creature might never get back
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home to its nest and children given the first contrary wind.
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There is one other problem. Desmond notes a fairly reasonably
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modus operandi for the pteranodon, i.e. that it had a throat pouch
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like a pelican, has been found with fish fossils indicating a
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pelican-like existence, soaring over the waves and snapping up fish
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without landing. That should indicate that, peculiarly amongst all
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of the creatures of the earth, the pteranodon should have been
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practically IMMUNE from the great extinctions of past ages.
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Velikovsky noted that large animals had the greatest difficulty
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getting to high ground and other safe havens at the times of floods
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and the global catastrophes of past ages and were therefore
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peculiarly susceptible to extinction. Ovid notes (Metamorphoses)
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that men and animals hid on mountain tops during the FLOOD, but
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that most died from lack of food during the hard year of the FLOOD.
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But high places safe from flooding were always there; oceans were
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always there and fish were always there. The pteranodon's way of
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life should have been impervious to all mishap; the notion that
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pteranodon died out when the felt effect of gravity on earth
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changed after the flood is the only good explanation.
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Back to Adrian Desmond for more on size as related to pterosaurs
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now:
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It would be a grave understatement to say that, as a flying
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creature, Pteranodon was large. Indeed, there were sound
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reasons for believing that it was the largest animal that ever
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could become airborne. With each increase in size, and
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therefore also weight, a flying animal needs a concomitant
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increase in power (to beat the wings in a flapper and to hold
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and manoeuvre them in a glider), but power is supplied by
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muscles which themselves add still more weight to the
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structure. -- The larger a flyer becomes the
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disproportionately weightier it grows by the addition of its
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own power supply. There comes a point when the weight is just
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too great to permit the machine to remain airborne.
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Calculations bearing on size and power suggested that the
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maximum weight that a flying vertebrate can attain is about 50
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lbs: Pteranodon and its slightly larger but lesser known
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Jordanian ally Titanopteryx were therefore thought to be the
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largest flying animals.
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Notice that the calculations mentioned say about 50 lbs is max for
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either a flier or a glider, and that experience from our present
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world absolutely coincides with this and, in fact, don't go quite
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that high; the biggest flying creatures which we actually see are
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albatrosses, geese etc. at around 30 - 35 lbs. Similarly, my
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calculations say that about 20000 lbs would be the largest
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theoretically possible land animal in our present world, and Jumbo
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the stuffed elephant which I've mentioned, the largest known land
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animal from our present world, was around 16000.
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But in 1972 the first of a spectacular series of finds
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suggested that we must drastically rethink our ideas on the
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maximum size permissible in flying - vertebrates. Although
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excavations are still in progress, three seasons' digging -
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from 1972 to 1974 - by Douglas A. Lawson of the University of
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California has revealed partial skeletons of three ultra-large
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pterosaurs in the Big Bend National Park in Brewster County,
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Texas These skeletons indicate creatures that must have
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dwarfed even Pteranodon. Lawson found the remains off four
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wings, a long neck, hind legs and toothless jaws in deposits
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that were non-marine; the ancient entombing sediments are
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thought to have been made instead by floodplain silting. The
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immense size of the Big Bend pterosaurs, which have already
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become known affectionately in the palaeontological world as
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'747s' or 'Jumbos', may be gauged by setting one of the Texas
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upper arm bones alongside that of a Pteranodon: the 'Jumbo'
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humerus is fully twice the length of Pteranodon's. Lawson's
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computer estimated wingspan for this living glider is over
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fifty feet! It is no surprise, says Lawson announcing the
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animal in Science in 1975, that the definitive remains of this
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creature were found in Texas.
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Unlike Pteranodon, these creatures were found in rocks that
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were formed 250 miles inland of the Cretaceous coastline. The
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lack of even lake deposits in the vicinity militates against
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these particular pterosaurs having been fishers. Lawson
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suggests that they were carrion feeders, gorging themselves on
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the rotting mounds of flesh left after the dismembering of a
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dinosaur carcass. Perhaps, like vultures and condors, these
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pterosaurs hung in the air over the corpse waiting their turn.
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Having alighted on the carcass, their toothless beaks would
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have restricted them to feeding upon the soft, pulpy internal
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organs. How they could have taken to the air after gorging
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themselves is something of a puzzle. Wings of such an
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extraordinary size could not have been flapped when the animal
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was grounded. Since the pterosaurs were unable to run in
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order to launch themselves they must have taken off
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vertically. Pigeons are only able to take-off vertically by
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reclining their bodies and clapping the wings in front of
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them; as flappers, the Texas pterosaurs would have needed very
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tall stilt-like legs to raise the body enough to allow the
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24-foot wings to clear the ground! The main objection,
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however, still rests in the lack of adequate musculature for
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such an operation. Is the only solution to suppose that, with
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wings fully extended and elevators raised, they were lifted
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passively off the ground by the wind? If Lawson is correct
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and the Texas pterosaurs were carrion feeders another problem
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is envisaged. Dinosaur carcasses imply the presence of
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dinosaurs. The ungainly Brobdignagian pterosaurs were
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vulnerable to attack when grounded, so how did they escape the
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formidable dinosaurs? Left at the mercy of wind currents,
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take-off would have been a chancy business.
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Lawson's exotic pterosaurs raise some intriguing questions.
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Only continued research will provide the answers.
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Note that Desmond mentions a number of ancillary problems, any of
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which would throw doubt on the pterosaur's ability to exist as
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mentioned, and neglects the biggest question of all: the
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calculations which say 50 lbs are max have not been shown to be in
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error; we have simply discovered larger creatures. Much larger.
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This is what is called a dilemma.
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Then I come to what Robert T. Bakker has to say about the Texas
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Pterosaurs ("The Dinosaur heresies", Zebra Books, pp 290-291:
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"Immediately after their paper came out in Science, Wann Langston and
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his students were attacked by aeronautical engineers who simply could
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not believe that the big Bend dragon had a wingspan of forty feet or
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more. Such dimensions broke all the rules of flight engineering; a
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creature that large would have broken its arm bones if it tried to
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fly... Under this hail of disbelief, Langston and his crew backed
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off somewhat. Since the complete wing bones hadn't been discovered,
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it was possible to reconstruct the Big Bend Pterodactyl [pterosaur]
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with wings much shorter than fifty feet."
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The original reconstruction had put wingspan for the pterosaur at over
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60'. Bakker goes on to say that he believes the pterosaurs really wre
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that big and that they simply flew despite our not comprehending how,
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i.e. that the problem is ours. He does not give a solution as to what
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we're looking at the wrong way.
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So much for the idea of anything RE-EVOLVING into the sizes of the
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flying creatures of the antedeluvian world. What about the possibility
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of man BREEDING something like a pteratorn? Could man actively breed even a
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50 lb eagle?
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David Bruce's "Bird of Jove", Ballentine Books, 1971, describes the
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adventures of Sam Barnes, one of England's top falconers at the time,
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who actually brought a Berkut eagle out of Kirghiz country to his home
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in Pwllheli, Wales. Berkuts are the biggest eagles, and Atlanta, the
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particular eagle which Barnes brought back, at 26 lbs in flying trim, is
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believed to be as large as they ever get. These, as Khan Chalsan
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explained to Barnes, have been bred specifically for size and ferocity
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for many centuries. They are the most prized of all possessions amongst
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nomads, and are the imperial hunting bird of the turko-mongol peoples.
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The eagle Barnes brought back had a disease for which no cure was
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available in Kirghiz, and was near to death then, otherwise there would
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have been no question of his having her. Chalsan explained that a
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Berkut of Atlanta's size would normally be worth more than a dozen of
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the most beautiful women in his country.
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The killing powers of a big eagle are out of proportion to its size.
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Berkuts are normally flown at wolves, deer, and other large prey.
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Barnes witnessed Atlanta killing a deer in Kirghiz, and Chalsan told him
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of her killing a black wolf a season earlier. Mongols and other nomads
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raise wheep and goats, and obviously have no love for wolves. While a
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wolf might be little more than a day at the office for Atlanta with her
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11" talons, however, a wolf is a major-league deal for an average sized
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Berkut at 15 - 20 lbs. Chalsan explained that wolves occasionally win
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these battles, and that he had once seen a wolf kill three of the birds
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before the fourth killed him. Quite obviously, there would be an
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advantage to having the birds be bigger, i.e. to having the average
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berkut be 25 lbs, and a big one be 40 or 50.
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It has never been done, however, despite all of the efforts since the
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days of Chengis Khan. We have Chengis Khan's famous "What is best in
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life..." quote, and the typical mongol reply from one of his captains
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involved falconry. They regarded it as important. Chengis Khan, Oktai,
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Kuyuk, Hulagu, Batui, Monke, Kubilai et. al. were all into this sport
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big time, they all wanted these birds big, since they flew them at
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everything from wolves and deer (a big berkut like Atlanta can drive its
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talons in around a wolf's spine and snap it) to leopards and tigers, and
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there was no lack of funds for the breeding program involved. Chengis
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Khan did not suffer from poverty.
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Moreover, the breeding of berkuts has continued apace from that day to
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this, including a 200 year stretch during which those people ruled
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almost all of the world which you'd care to own at the time, and they
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never got them any bigger than 25 lbs or so.
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Remember Desmond's words regarding the difficulty which increasingly
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larger birds will experience getting airborne from flat ground? Atlanta
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was powerful enough in flight, but she was not easily able to take off
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from flat ground. Barnes noted one instance in which a town crank
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attacked Atlanta with a cane and the great bird had to frantically run
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until it found a sand dune from which to launch herself. This could
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mean disaster in the wild. A bird of prey will often come to ground
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with prey, and if she can't take off from flat ground to avoid trouble
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once in awhile... it would only take once. Khan Chalsan had explained
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the necessity of having the birds in captivity for certain periods, and
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nesting wild at other times. A bird bigger than Atlanta would not
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survive the other times.
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One variety of pteratorn, however, judging from pictures which have appeared
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in Science Magazine, was very nearly a scaled-up golden eagle weighing
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170 lbs or so, with a wingspan of 27' as compared to Atlanta's 10. In
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our world, that can't happen. Just another one of those things for
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which establishment science has no answer.
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--
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Ted Holden
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HTE
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