New Delhi: An international team of palaeontologists have answered the question of why there are no deep diving crocodiles like whales and dolphins. The research suggests that thalattosuchians, prehistoric kin of modern crocodiles that lived at the same time as the dinosaurs could not become deep divers because of the giant sinuses in their large snouts. During the 10 million years over which whales and dolphins took to the seas, the bone-enclosed sinuses reduced in size, and were replaced by air sacs that developed outside the skulls. The relocation of the sinuses allowed the cetaceans to withstand the pressures of deep-sea diving, allowing dolphins to........