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Birds Ancestors.
Scientists in general agree that both birds and mamals developed from reptiles or reptilelike animals, reptiles, birds, and mamals together with amphibia having origanted in the lower border of fishes. It appears that long before birds were involved there existed certain species of flying reptiles among them being the Pterodactyl, found in the jurassic rocks of [Barvaria]. These flying lizards had hands with five fingers, the fifth being about ten times as long as the others and between the little finger and the first and second joints of the leg was stretched a skin membrane similar to that of bats.
With such a wing continous flight was possible. These Pterodactyls may have had their origin in other lizards which had not the power of continous flight, but which could only fly to some tree top or other high point and jump after its prey, using its skin appendages just as a flying squirrel does today.
It seems probably that the conditions which brought about aerial soaring or real flight may have been an over-crowding of seas and lands so that food became scarce and these animals found it necessary to invade the [the] for food.
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The Pterodactyl was not the ancestor of our birds though donbtlers the same condition which led up to this type were for the bird type.
The very oldest bird of which we have record of is the fossil [archaeopteryx] from the jurassic rocks of Barvaria. This bird possessed teeth, a long lizard like tail, with two rows of lateral feathers extending backward from the arm for flyers. A comparison of the [Archacopterx] with certain of the ancient lizards shows that birds and reptiles were one scarcely distinguishable except for the presence of feathers on birds.
The great instrument of dry land invasion was the back bone and the great instrument of aerial invasion was the wing, probably
in reptites and surely perfected in birds It may be possible that there were in some of the reptites soft modifications of the scales which greatly decreased their specific gravity and made it possible for them to spring up from the ground and for a short period flap about suspended in the atmosphere by exhausted labor. This tendency to fly brought about replacement of scales by feathers.
Birds and reptiles show a similar
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origin by these common characteristics. 1. Both produce a large egg, found nowhere else except monotremes on Duckbills, a three corned link between birds, reptiles and mamals. 2. In neither is there a complete diaphragm below the heart. 3. In each there is but one ball and socket joint where the head turns on the neck, where as the mamals and amphibians have two. 4. In each the lower jaw is connected to the by an intervening (quadrate) bone not found in mamals. 5. Neither birds nor reptiles pass through a tadpole starte, as do the amphibians, or have special glands (mammae) to nourish their young, as do the mamals.
Though birds are hot blooded and reptiles cold blod, birds have feathers and be[...] have scales, never the less scientists are generally agreed that both should be placed in the same class. Whether all birds have sprung from an individual ancestor is a question on which all are not agreed.
Many think that before birds wore feathers they flew by skin appendages and even before this they crawled about in trees walking up right and clinging to the branches by their hooked
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wings.
A few modern birds still do this. It is possible that the Archacopteryx could not rise in flight from the earth escept against strong winds, to go with the wind possibly they had to flutter backward just as many insects do yet.
Their long tail was very helpful in preserivng the birds balance while in air, but later it was shorter to allow birds the more easily to turn quickly and fly faster.
Why than did birds put on feathers? Live in the air requires the expenditure of much more energy than lift on land or in the water. In the air medium a vast ammount of fuel must be consumed, so much that the normal temperature of a bird varies with the species from 102° to 110°. The normal temperature of man is 98 1/2. Excepting some of the rapid flying insects no animal works at such a high temperature as the birds; [a dragon fly can outstrip a swallow]; it can do more than any birdit can fly foreward, backward, and sidewise, to right or left and change its course instantly without turning]; no other vertebrate expends so much energy per hour for so long a period.
To retain the heat in this bird furnace
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nature jacketed it with underwear of down and outer garments of feathers, and the greater the danger of heat reaction the greater the thickness and extent of this jacketing. Since feathers were not necesary to flight it is not probable that birds were clothed with feathers until this extra energy began to show. [it] seff. Nature being [...] to make the time became lavish in her gift.
Scales were not suited for heat conservation in fast they increased heat induction.
A cold blooded animal is one that has the temperatire of its surroundings and it necesarily [must] become [imured], with out shock, to a constantly cold, watery environment. Its body heat produced by internal [...] would thus be [lift] low by the conduction of that heat through the scales and no shock would be experienced from a medium of low temperature.
Birds were destined to inhabit a regine of [divversiued] temperatures. Those best clothed could migrate over the greatest range of climate in search of food. For this purpose feathers are admirable [reiment]; drawn close they allow greater radiation and cooling fluffed out; they increase the depth of dead air space about the bird and conserve more heat. Fishes and reptiles have pres in the skin from which secretions [pove] for various purposed. Rapid