In The Lost World (1912) by Arthur Conan Doyle, the characters discover a plateau in the South American jungle where prehistorical life forms still exist. The first harbinger of this remarkable biota is a pterodactyl, and after ascending atop the plateau, the protagonists encounter many more of the creatures.
Bizarrely, it seems to me, the story treats the pterodactyls are self-evidently the most horrible of monstrosities. (This feels utterly weird to me, but for most of my childhood, I had stuffed pterodactyls hanging from my bedroom ceiling. However, I am certainly not the only individual to find pterodactyls rather cute.) At first, Conan Doyle's tone seems fairly reasonable.
Well, suddenly out of the darkness, out of the night, there swooped something with a swish like an aeroplane. The whole group of us were covered for an instant by a canopy of leathery wings, and I had a momentary vision of a long, snake-like neck, a fierce, red, greedy eye, and a great snapping beak, filled, to my amazement, with little, gleaming teeth. The next instant it was gone—and so was our dinner. A huge black shadow, twenty feet across, skimmed up into the air; for an instant the monster wings blotted out the stars, and then it vanished over the brow of the cliff above us. We all sat in amazed silence round the fire, like the heroes of Virgil when the Harpies came down upon them.
However, subsequent encounters are described even more floridly.
If, as Lord John said, the glade of the iguanodons will remain with us as a dream, then surely the swamp of the pterodactyls will forever be our nightmare.
...
Creeping to his side, we looked over the rocks. The place into which we gazed was a pit, and may, in the early days, have been one of the smaller volcanic blow-holes of the plateau. It was bowl-shaped and at the bottom, some hundreds of yards from where we lay, were pools of green-scummed, stagnant water, fringed with bullrushes. It was a weird place in itself, but its occupants made it seem like a scene from the Seven Circles of Dante. The place was a rookery of pterodactyls. There were hundreds of them congregated within view. All the bottom area round the water-edge was alive with their young ones, and with hideous mothers brooding upon their leathery, yellowish eggs. From this crawling flapping mass of obscene reptilian life came the shocking clamor which filled the air and the mephitic, horrible, musty odor which turned us sick. But above, perched each upon its own stone, tall, gray, and withered, more like dead and dried specimens than actual living creatures, sat the horrible males, absolutely motionless save for the rolling of their red eyes or an occasional snap of their rat-trap beaks as a dragon-fly went past them. Their huge, membranous wings were closed by folding their fore-arms, so that they sat like gigantic old women, wrapped in hideous web-colored shawls, and with their ferocious heads protruding above them. Large and small, not less than a thousand of these filthy creatures lay in the hollow before us.
The other giant reptiles the characters meet, while they may be dangerous or docile, never are described with the same utter revulsion that the pterodactyls appear to engender.
I passed close to the pterodactyl swamp, and as I did so, with a dry, crisp, leathery rattle of wings, one of these great creatures—it was twenty feet at least from tip to tip—rose up from somewhere near me and soared into the air. As it passed across the face of the moon the light shone clearly through the membranous wings, and it looked like a flying skeleton against the white, tropical radiance. I crouched low among the bushes, for I knew from past experience that with a single cry the creature could bring a hundred of its loathsome mates about my ears. It was not until it had settled again that I dared to steal onwards upon my journey.
When they bring a specimen back, it doesn't go over well.
An instant later, with a scratching, rattling sound, a most horrible and loathsome creature appeared from below and perched itself upon the side of the case. Even the unexpected fall of the Duke of Durham into the orchestra, which occurred at this moment, could not distract the petrified attention of the vast audience. The face of the creature was like the wildest gargoyle that the imagination of a mad medieval builder could have conceived. It was malicious, horrible, with two small red eyes as bright as points of burning coal. Its long, savage mouth, which was held half-open, was full of a double row of shark-like teeth. Its shoulders were humped, and round them were draped what appeared to be a faded gray shawl. It was the devil of our childhood in person. There was a turmoil in the audience—someone screamed, two ladies in the front row fell senseless from their chairs, and there was a general movement upon the platform to follow their chairman into the orchestra. For a moment there was danger of a general panic. Professor Challenger threw up his hands to still the commotion, but the movement alarmed the creature beside him. Its strange shawl suddenly unfurled, spread, and fluttered as a pair of leathery wings. Its owner grabbed at its legs, but too late to hold it. It had sprung from the perch and was circling slowly round the Queen's Hall with a dry, leathery flapping of its ten-foot wings, while a putrid and insidious odor pervaded the room. The cries of the people in the galleries, who were alarmed at the near approach of those glowing eyes and that murderous beak, excited the creature to a frenzy. Faster and faster it flew, beating against walls and chandeliers in a blind frenzy of alarm.
My question is simple: Is there any known reason why Conan Doyle thought that the pterodactyls would be so self-evidently horrifying? The author was not a very deep thinker, but the strength of his reaction to the idea of flying reptiles suggests that there was something underlying his reasoning. Was he perhaps particularly afraid of bats, with their similarly membranous wings? Did he or anyone else shed further light on how this seemingly strange view originated?