Evolution, Vol. 23, No. 1 (Mar., 1969), pp. 131-152 (22 pages) Important structural adaptations of the nasal sac, as well as the development of the nasal and choanal tubes, nostrils and choanae, were ...

On this planet there are many different ecosystems. Most of these ecosystems are very competitive and different species struggle to survive. Some animals have an edge over their competition and these ...