The study of the avian chondrocranium commenced with the classic and ex- cellent monographs of W.K. Parker (1866, 1869, 1875, 1876, 1890) who described the development in the ostrich tribe, the Gallinaceae and various other birds. T.J. Parker (1888, 1891) continued these investigations in Apteryx. The next milestone was the detailed study of the development of Tinnunculus (Suschkin 1899), followed by contributions from Tonkoff (1900), Gaupp (1906) and Sonies (1907). With improved techniques, Sonies (1907) could elucidate various new aspects of the chondrocrania of Gallus and Anas. A major contribution was made by de Beer and Barrington (1934), who not only gave a detailed description of the development of the chondrocranium of Anas but also standardised the nomenclature and elaborated on the various morphological problems of the avian chondrocranium.
After Brock's (1937) study of the morphology of the chondrocranium of the ostrich, contributions came from Kesteven (1941, 1942), Hofer (1945, 1949, 1954), Slaby (1951 a, b, 1952, 1958), Barnikol (1952), Starck (1941, 1955, 1960), Lang (1955,1956), May (1961), Muller (1961,1963), Macke (1969), Goldschmid (1972) and Smit and Frank (1979).