On 1 December 1923, he started his regular duty at the
Schönbrunn Zoo. Four months later he was named scientific director and eventually became palaeontologist and expert for zoological science on domestic animals. On 1 December 1925 he became the only director with full responsibilities. In March 1934, Antonius was officially dismissed, due to accusations of being an active member of the
NSDAP which was illegal in Austria. Antonius denied this allegation and sued successfully. He was reinstalled as director on 4 January 1937. His commitment for Schönbrunn was extremely important for the survival of the zoo. Before World War I, the zoological garden ranked among the biggest and most beautiful zoos in the world. As there were shortages in feed during war, the livestock dropped extremely. In fall 1921, the zoo was about to close. Already in 1918, Antonius had written an exposé on how to modernise the outdated enclosures. Due to support from the Viennese population, private sponsors, the Hilfsaktion für den Ausbau des Schönbrunner Tiergartens and the livestock supplies from the animal dealer Alfred Weidholz, the number of animals increased, the cages and enclosures were improved and new projects, like the aviary for birds of prey or the monkey house, were realised. Antonius also introduced new media, like the display of
dioramas in 1934. The
dioramas showed landscapes and animals of Austria's
prehistory. They were painted by the artist Franz Roubal. The display of dioramas did not succeed with the public. The dioramas were destroyed in
World War II. Antonius served as vice-president of the
International Union of Zoo Directors from 1938 to 1945. He also was a member of the
Zoological Society of London. Additionally he taught as an associate professor at university. == Zoological biology ==