本篇文章共分 4 段，將科學界對於神秘的翼龍體型結構、行走方式與飛行能力一一加以說明陳述，藉以建立這種目前滅絕生物的生理與行動特徵。

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Characteristics of Pterosaurs 翼龍的特徵

1. 科學界對翼龍的早期重建

   The extinct flying reptiles called pterosaurs were the second group of animals (after insects) to evolve flight. Most pterosaurs were about the size of modern seagulls. A few were as small as sparrows, but some of the later species were the largest flying animals that have ever lived. In 1817, Theodore Von Soemmerring published the first description of a pterosaur fossil, and thinking that it was of an unusual bat species, he drew his reconstruction with a very batlike posture and wing. His early reconstruction of a pterosaur has haunted the public and scientific perception of pterosaurs ever since Soemmerring's reconstruction is understandable given that he was the first to try to describe a pterosaur, that few naturalists of the time accepted the idea of major groups of extinct animals, and that both pterosaurs’ and bats’ wings consist of a membrane supported by enormously elongated finger bones. Soemmerring showed his pterosaur with the laterally directed legs and reoriented feet of bats and with the wing membrane stretching from the arm and finger along the sides of the body and legs all the way to the ankle. The reconstruction also included a membrane stretching between the legs, similar to that in bats. Even though other scientists developed less batlike descriptions of pterosaurs in the late 1800s, the popular literature, and even some scientific literature, continued to describe pterosaurs as batlike into the 1980s.

   被稱為翼龍的已滅絕飛行爬行動物是第二類進化出飛行的動物（繼昆蟲之後）。大多數翼龍的大小與現代海鷗差不多。少數像麻雀一樣小，但一些後來的物種是有史以來最大的飛行動物。1817 年，西奧多．馮．索默林發表了第一份關於翼龍化石的描述，認為這是一個不尋常的蝙蝠物種，他用非常像蝙蝠的姿勢和翅膀繪製了他的重建圖。他對翼龍的早期重建一直困擾著公眾和科學界對翼龍的看法，因為 索默林是第一個嘗試描述翼龍的人，同時當時很少有自然學家接受滅絕動物的主要群體的想法，還有翼龍和蝙蝠的翅膀都是由巨大的拉長的指骨支撐的薄膜組成，所以他的重建是可以理解的。索默林展示了他的翼龍與蝙蝠的側向腿和重新定向的腳，並且翼膜從手臂和手指沿著身體和腿的兩側一直延伸到腳踝。重建工作還包括在兩腿之間延伸的膜，與蝙蝠的膜相似。儘管其他科學家在 19 世紀末對翼龍進行了不那麼像蝙蝠的描述，但流行文獻，甚至一些科學文獻，一直到 20 世紀 80 年代仍將翼龍描述為像蝙蝠。

2. 翼龍的行走方式

   Bats perch by hanging upside down from tree limbs and roofs of caves. Though many are surprisingly agile climbers, bats are generally awkward when crawling on level surfaces. Did pterosaurs also hang upside down and avoid landing on the ground? Until recently, some paleontologists thought they did, but most scientists now agree that pterosaurs got around on the ground reasonably well. What is still uncertain is whether pterosaurs walked on all fours or just on their hindlegs. Pterosaurs' ancestors were bipedal (two-footed) and used their tails to balance their forward-tilted trunks and heads. Early pterosaurs also had long tails and probably could have run on their hindlegs, certainly handy for an animal with wings for forelimbs. These early pterosaurs, however, could have used their forelimbs for walking because their arm and hand bones were only slightly enlarged—most of the wing was supported by the gigantic fourth finger.

   蝙蝠藉由倒掛在樹枝和洞頂來棲息。儘管許多蝙蝠具有驚人的敏捷攀爬能力，但當在平坦的表面上爬行時，卻通常顯得笨拙。翼龍是否也倒掛並避免落地？直到最近之前，一些古生物學家認為它們的確如此，但現在大多數科學家都同意，翼龍在地面上的活動能力相當不錯。仍然不確定的是，翼龍是用四肢行走，還是僅僅用它們的後腿行走。翼龍的祖先是兩足動物（雙腳），用它們的尾巴來平衡它們向前傾斜的軀幹和頭部。早期的翼龍也有長長的尾巴，可能可以用它們的後腿奔跑，這對一種前肢有翅膀的動物來說當然很方便。然而，這些早期的翼龍可以用它們的前肢來行走，因為它們的臂骨和手骨只是稍微擴大了一些—大部分的翅膀是由巨大的第四指支撐的。

3. 晚期翼龍的行動方式

   Later pterosaurs are more enigmatic: their arms and especially their hands seem too long to be used comfortably for walking, but their tails were too short to counterbalance their bodies if they walked just on their hindlegs. Birds also have short, stubby tail skeletons, but they manage to walk quite well on their hindlegs. Birds manage this by angling the thighs forward to get their feet under the body's center of gravity. They hold their thighs at this unstable angle with extensive hip and thigh muscles. Some researchers have suggested that pterosaurs’ hipbones were too small to anchor extensive thigh-positioning muscles, but others have responded that pterosaurs’ leg and foot bones are so strikingly birdlike that pterosaurs must surely have walked like birds. Recently, however, some pterosaur experts have concluded that a number of fossil trackways—trails of preserved footprints—were made by pterydactyloid pterosaurs, and these animals clearly walked on all four limbs. Perhaps some early pterosaurs walked on their hindlegs, but according to current evidence, most species probably walked on all fours. In any case, large pterosaurs, with eight or ten-meter wingspans and weighing as much as an adult human, do not seem likely candidates for a batlike existence confined to clambering about in trees and hanging upside down from branches.

   後來的翼龍則更加神秘：它們的手臂，特別是它們的手掌似乎太長了，無法舒適地用於行走，但它們的尾巴又太短了，如果它們只是用它們的後腿行走，就無法平衡它們的身體。鳥類也有短而粗的尾巴骨架，但它們卻能熟練地用它們的後腿行走。鳥類通過將大腿向前傾斜以使它們的腳處於身體的重心之下來實現這一點。它們用大量的臀部和大腿肌肉將大腿保持在這個不穩定的角度。一些研究人員認為，翼龍的髖骨太小，無法固定大量的大腿定位肌肉，但也有人回應說，翼龍的腿骨和腳骨與鳥類是如此驚人的相似，所以翼龍肯定是像鳥類一樣行走。然而，最近，一些翼龍專家認為，一些化石軌跡—保存下來的腳印軌跡—是由翼龍亞目留下的，這些動物顯然是用四肢行走的。也許一些早期的翼龍用它們的後腿行走，但根據目前的證據，大多數物種可能是用四肢行走。在任何情況下，大型翼龍，翼展有 8 米或 10 米，體重與成年人類相當，似乎不可能像蝙蝠一樣只在樹上爬來爬去，倒掛在樹枝上。

4. 翼龍的飛行能力

   Pterosaurs also possessed some obvious adaptations for powered flight. They had large sternums (breastbones) for attaching powerful flight muscles, well-developed shoulder bones to carry the body's weight in flight, and air-filled bones to lighten the skeleton. Some even had a furcula (a fused breastbone also found in birds): perhaps to flex like a spring and help raise the wings during the upstroke. How competent were they at flying? The original batlike reconstructions, along with their classification as reptiles, suggested to many earlier biologists that pterosaurs were only gliders. Biologists now, however, generally agree that pterosaurs were capable of powered, flapping flight. Indeed, the shoulder joint is clearly specialized for the down-and-forward, up-and-back movement of normal flapping.

   翼龍還擁有一些明顯的適應動力飛行的特徵。它們有大的胸骨（胸骨）來連接強大的飛行肌肉，有發達的肩骨來承載飛行中的身體重量，還有充滿空氣的骨頭來減輕骨架重量。有的甚至有一個 furcula（一種在鳥類中也能找到的融合的胸骨）：也許是為了像彈簧一樣彎曲，在上衝過程中幫助提高翅膀。他們的飛行能力如何？最初的蝙蝠式重建，加上它們被歸類為爬行動物，使許多早期的生物學家認為翼龍只是滑翔機。然而，現在的生物學家普遍認為，翼龍有能力進行動力、拍打飛行。事實上，肩關節顯然是專門用於正常拍打的向下和向前、向上和向後的運動。