The dinosaur planet omnibus - Anne McCaffrey

DINOSAUR PLANET: On Earth they had died out 70 million years ago. But on Ireta they ruled in all their bizarre splendour. The Dinosaurs. Relics from a forgotten age, they roamed a planet as mystifying as any in the galaxy. And the expedition sent to explore it was trapped within its toils as quickly and mysteriously as their relief ship disappeared. And worse. For the Heavyworlders, half the expedition's personnel, reverted to type, and as predatory carnivores systematically hunted down their colleagues. Only the frozen sleep of cryogenics offered an escape. But for how long?

SURVIVORS: Much time has elapsed - how much is hard to tell, but at least two generations - and the survivors emerge from their hibernation. Ireta, the Dinosaur Planet, has changed. A rescue ship is on its way, but even as hope begins to spring, new problems arise. What are the motives of the mysterious Theks? Above all, what could possibly be the cause of the mindless hostility of the Heavyworlders?