Dave Wolverton
Serpent Catch
1991

"Tull, son to a human father and a Neanderthal mother, feels doomed to toil his life away as a common field hand on the moon Anee. But his is a time Earth's paleobiologists could not have foreseen. Long ago they established Anee as a vast storehouse of extinct species, each continent home to life forms of a different era. For a thousand years the starfarers' great sea serpents formed a wall of teeth and flesh that protected Tull's homeland from the ravaging dinosaurs that swam across the ocean from Hotland. Now the serpents are gone.

To save his home, Tull must seek a distant river in the slave nation of Craal, where young serpents can be found. Legend has it that Adjonai, the Neanderthal god of terror, is king of Craal. Yet only by facing this dark enemy can Tull hope to bring home his serpent catch alive."