The rain was still falling when the clouds lightened once more to the rising sun. Lampert was getting used to navigating the canyon by radar, and was an excellent pilot anyway; so he did not have too much trouble in locating the shelf where Sulewayo and Krendall had been working. Getting the men down to it was not particularly difficult, though rather nerve-racking. Krendall went first, unburdened except for his personal equipment. Then he steadied the ladder for Sulewayo who had the cutter strapped across his shoulders. The steadying hand was needed. Climbing down a rope ladder when loaded "top-heavy" can be an extremely awkward bit of activity. Had the pilot above been any less capable, it would probably have been impossible.

The ledge was wet, but fortunately not particularly slippery. The men set their equipment on the ground at the point where their cut entered the crack in the cliff, and without delay set to work. The tunnel was deep enough now to shelter the one actually cutting from the rain, so at first they took turns at this operation.

The cutting machine Lampert had provided was a sort of diamond-toothed chain saw capable of a two-meter extension. Ordinarily it was not the sort of thing a paleontologist would consider using so close to a specimen; but the men were fairly sure by now of the general extent of the thing they were uncovering. Even so, they used the saw only on the side of their tunnel away from the visible remains. They speedily widened the passage enough to permit them both to get inside and work on the face of the exposed material; but they still used hand tools whenever there was any suspicion that a bone might be about to appear. Work proceeded several times as fast as it had the day before.

They tried cutting another tunnel on the opposite side of the fossil, but this proved rather awkward. The creature was close to this side of the crack, and they had to cut limestone as well as the softer tuff. The saw proved capable of handling this—it would have handled granite without trouble—but went a little more slowly. Eventually, however, the two men were working on opposite sides of the fossil, each in a tunnel extending some two meters into the cliff face.

Half a day's work uncovered the leg bones sufficiently to show that Krendall's first idea had been right. There were only the two major joints, each a trifle shorter than the corresponding parts of the human skeleton. The lower leg was single rather than double, however; knee and ankle both consisted of ball-and-socket joints; and with this fact determined the men paused for thought.

"Now why," mused Krendall aloud, "should any sort of creature need that articulation?"

"Could that foot be a hand instead?" asked Sulewayo.

Of course, questions like that should have awaited the results of detailed examination in a laboratory. Equally of course, the two men proceeded to clear one of the "feet" a little more thoroughly in order to find out for themselves. The answer was not helpful, though.

"He might have picked up a twig with it, but he couldn't have held it any more tightly than I can in my toes," was Krendall's verdict. "It's a bigger and flatter foot than ours. But it's a foot—nothing more."

"Maybe a swimming organ on the side?" suggested Sulewayo cautiously.

"Seems doubtful. If that joint evolved for such a purpose, I should think there'd be a corresponding modification in the foot bones, too—say a flattening such as you see in the paddles of some of the Mesozoic sea reptiles of Earth."

"Reasonable."

"But not necessarily right. That I admit. Anything else strike you?"

"Yes, though it makes the joints still more unbelievable."

"What?"

"The foot itself. Unless some rather remarkable distortion has occurred, it had both longitudinal and transverse arches, like yours and mine—which suggests strongly that this thing's ancestors had been walking erect on two legs for some hundreds of thousands of generations." Krendall raised his eyebrows at this, and silently examined the bony structure before them for several minutes.

"I—hadn't—spotted—that," he said slowly. He looked in silence for several more seconds. Then the two men, moved by a single thought, went to the other end of the exposed leg and began to clear the hip joint and pelvic region. They worked almost in silence, understanding each other perfectly, like an experienced surgical team; and gradually the equivalent of a pelvic girdle and lower end of a spinal column were cleared sufficiently to show their general nature.

It was at this point that the helicopter returned; but neither man noticed the fact until McLaughlin had called several times from the open ladder hatch. They climbed silently and thoughtfully up to the flyer; but Mitsuitei's first question started the talk flowing.

It did not end for a long, long time.

Krendall, with difficulty, held interruptions of his more volatile companion.

"There can be only the slightest doubt that this thing we're uncovering walked erect on two legs," he reported. "The feet; the way the pelvis is modified to support internal organs; the fusing of the lowest vertebrae with the pelvic girdle to form a weight carrying foundation—they all point the same way. The only thing hard to understand is the knee and ankle joints. If we had them, it would be virtually impossible for us to hold our legs rigid. Perhaps some really remarkable musculature—"

"Or a cartilage structure which has not been preserved," cut in Sulewayo.

"Or some such thing as that, would explain it. I don't know. The creature is good for several Ph.D. theses just as it lies—and probably an equal number of nervous collapses when we get it out."

"I find myself strongly desirous of seeing its skull," remarked Lampert. Sulewayo glanced at him sharply.

"You, too?" asked the young paleontologist. "I was hoping I was the only one crazy enough to have thought of that." Mitsuitei smiled openly, an almo............