![[과학마녀 일리의 과학용어 따라잡기] 깃털, 원기](http://dl.dongascience.com/uploads/article/thumbnail/202014/20200712-086.png)
깃털(feather) 깃털은 새의 몸 표면을 덮고 있는 털이에요. 파충류의 비늘이나 포유류의 털처럼 겉 피부가 변형된 기관인데, 중심에서 뻗은 깃이 있다는 차이가 있지요.우리는 보통 깃털의 가장 중요한 목적이 새의 비행을 도와주는 것으로 생각해요. 그런데 깃털의 쓰임새는 더 다양해요. 공작 ...
따르면 동물의 발생초기에 형성되는 초기 표피세포층은 발생조건에 따라 비늘(scale) 깃털(feather) 또는 털(hair)로 분화되는데 결코 이들의 중간형태로는 분화되지 않는다는 것이다. 또한 단속평형설에서 주장하는 진화양상을 보인다고 가정하면 새로운 환경에 도전하는 소수의 개체가 짧은 기간 내에 ...
their mass, fall at the same speed(if such things as air resistance are disregarded). In a vacuum, a cannonball and a feather drop at the same rate. This is called the principle of equivalence.This was first shown in a very crude way by Galileo four centuries ago, and since then, it has been proved by experiments that have been progressively more accurate.There is just one way in which the ...
have at the base of their tail. This means that the fossil had a bird-tail instead of a lizard-tail. A bird-tail has feathers that act as a brake on flight when the bird is landing-again evidence that the fossil could fly.Unfortunately, no skull was found, so we can't tell how that might resemble modern birds and what kind of beak, if any, it might have had. However, further searches may well ...
than papyrus ever was and is in more plentiful supply. The Egyptians applied ink with fine brushes, but since then feather quills, steel pens, fountain pens, ball-point pens and so on have been used - but it all comes under the general heading of ink-on-paper. Originally, sheets of papyrus were pasted to each other, side by side, into a long continuous sheet that was rolled up into a tight ...
that they must have been warm-blooded, which would mean that they were covered with hair. (Not feather, If they had feathers we would probably have found impressions of them on and occasional pterosaurs fossil, but we haven's)To appreciate the difficulty flight must have posed for these creatures, consider, the May, 1986. demonstration at Andnews Air Force Base near Washington,D.C., of a ...
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