Dinosaur Planet by Anne McCaffrey

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?