It was the reverse of what it should have been. In the top few feet, there were plentiful fossil remains, mostly of the four species of mammals. The squirrel-like creature and the far larger grazing animal were the forest dwellers. Of the plains animals, there were only two, in size fitting neatly between the extremes of the forest dwellers.
After the first few feet, which corresponded to approximately twenty thousand years, he found virtually no fossils. Not until he reached a depth which he could correlate to the Late Carboniferous age on Earth did fossils reappear. Then they were of animals appropriate to the epoch. At that depth and below, the history of Glade was quite similar to Earth's.
Puzzled, he checked again in a dozen widely scattered localities. The results were always the same—fossil history for the first twenty thousand years, then none for roughly a hundred million. Beyond that, it was easy to trace the thread of biological development.
In that period of approximately one hundred million years, something unique had happened to Glade. What was it?
On the fifth day his investigations were interrupted by the sound of the keyed-on radio.
"Marin."
"Yes?" He flipped on the sending switch.
"How soon can you get back?"
He looked at the photo-map. "Three hours. Two if I hurry."
"Make it two. Never mind the oil."