Uls of Gor
This research is done on the series of books written by John Norman, the comments in italics are mine and my point of view.
Woman of Gor
Also, at night, crossing the bright disks of Gor's three moons might occasionally be seen the
silent, predatory shadow of the Ul, a giant pterodactyl ranging far from its native swamps in the
delta of the Vosk.

A brightly plumaged bird sprang from the rushes to my left, screaming and beating its sudden way
into the blue sky. In a moment it had darted again downward to be lost in the rushes, the waving
spore stalks, the seed pods of various growths of the Gorean tidal marshes. Only one creature in
the marshes dares to outline itself against the sky, the predatory UI, the winged tharlarion.
Raiders of Gor, page 1

The rence growers, in spite of the value of their product, and the value of the articles taken in
exchange for it, and the protection of the marshes, and the rence and fish which give them ample
sustenance, do not have an easy life. Not only must they fear the marsh sharks and the
carnivorous eels which frequent the lower delta, not to mention the various species of aggressive
water tharlarion and the winged, monstrous, hissing, predatory UI, but they must fear, perhaps
most of all, men, and of these, most of all, the men of Port Kar. Raiders of Gor, page 8

I saw a Ul, the winged tharlarion, high overhead, beating its lonely way eastward over the marsh.
Raiders of Gor, page 61

I awakened stiff in the cold of the marsh dawn, hearing the movement of the wind through the
dim sedges, the cries of an occasional marsh gant darting among the rushes. Somewhere in the
distance I heard the grunting of tharlarion. High overhead, passing, I heard the squeals of four
Uls, beating their way eastward on webbed, scaled wings. I lay there for a time, feeling the rence
beneath my back, staring up at the gray, empty sky. Raiders of Gor, page 77

We heard, outside, the screaming of a predatory ul, a gigantic, toothed, winged lizard, soaring
over the marshes. Savages of Gor, page 18

We heard, again, the screaming of the ul outside the building. The tarns in the tarn cot moved
about. The ul will not attack a tarn. The tarn could tear it to pieces. Savages of Gor, page 19

I had never been so close to such a thing before. I had not realized they were so large.
It was five days since I had freed myself of the manacles. I had been moving northward, across
the sluggish current, for three days.
It opened its wings, suddenly. Their span must have been twenty-five to thirty feet Gorean.
Vagabonds of Gor, page 179

I had also seen then, as I had come closer, the small head of the creature, small considering the
size of its body, and the span of its wings, lift up, above the rence, with its long narrow, toothed
jaws, like a long snout or bill, with that long, narrow extension of skin and bone in the back,
balancing the weight of the long, narrow jaws, contributing, too, given the creature's weight and
general ungainliness in structure, to stability in flight, particularly in soaring. Vagabonds of Gor,
page 180

The creature had turned to regard me.
It had opened its wings, suddenly. Their span must have been twenty-five to thirty foot Gorean.
Then it closed them, folding them back, against its body.
I was quite impressed with it. Never had I been so close to such a thing before.
It uttered a hissing, grunting sound, expelling air from its lungs. It had a long, snakelike tail,
terminating with a Hat, spadelike structure. This tail lashed, the spadelike structure dashing
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Again it opened its wings. These are of skin and stretch from the jointed, hind legs, clawed, of the creature to an extremely long,
fourth digit on its clawed hand. It hissed at the tharlarion near the pole. One moved away. The other stood its ground, opening its
own jaws, hissing.
The creature then snapped its wings, again and again. I had not realized the blast that might be created from that, and was thrown
back, stumbling, into the rence. I fought my way forward, again, then, against the gusts, as though through a storm in the Tahari. I
held my arm before my face. I heard the short-legged tharlarion make a strange noise and saw it lifted from the sand and shaken. I
heard it's back snap. With a beating of the giant wings the creature ascended, struggling with the weight of the tharlarion, and then,
after a moment, perhaps from a height of a hundred feet or so, dropped it into the marsh. I did not see it hit the water, for the rence,
but I saw, two or three hundred feet away, the splash. Its shadow was then over the water, rapidly approaching, and, in a moment,
its clawed feet striking down into the sand, it alit on the beach, much where it had been before. The whole thing had taken no more
than a few Ihn. I had not realized the power of the creature, or that it could lift that much weight. The weight of a man, then, or a
woman, would have been nothing to it. There is little wonder, I thought, that many take the predatory ul, the winged tharlarion, to
be the monarch of the delta. Vagabonds of Gor, page 182

“There may be others,” she said.
“Probably not in this vicinity,” I said. The larger uls, as opposed to the several smaller varieties, some as small as jards, tend to `e
isolated and territorial. Vagabonds of Gor, page 203