From the flap:
"What was it that stalked the peak of San Lorenzo? Some people in Redwood Cove said it was unnatural, that it was a monster, a demon. To Mr. Looper, Curator of the Redwood Cove Natural History Museum, it was an Elasmasaurus californicus. Then, one day, to Jennifer and Tom it became the churnadryne.
It was late afternoon when they set out from the museum to find the creature. Everyone along the way warned them against it, and cautioned them to be home before dark. But it was just before dark when out of the fog loomed the huge shadow - graceful, beautiful, and terrifying.
The whole town was drawn into the mystery. Just what had Tom and Jennifer seen? There were people who laughed, those who were hysterical with fear, and there were scientists and newspapermen who believed in it. Mr. Looper was to risk his life trying to learn the secret of the beast.
Fans of Mrs. Cameron's Mushroom Planet series will be delighted with this new and excitingly different mystery."
Pocket Books, 1972, $0.75