Imperial diptych offerings to the emperor. However, the fact that the Barberini ivory was almost certainly not a diptych, but some kind of imperial icon without a second panel is a serious argument against the existence of the imperial diptych type. The two panels representing the empress Ariadne, in the Bargello in Florence and the Kunsthistorisches Museum in Vienna, also belong to the hypothesied imperial diptych type. They are the only central panels of such a diptych (other than the Barberini ivory) to survive, since all other fragments of such diptychs are from side panels. Imperial diptych In Late Antiquity, an imperial
Imperial pigeon the Australian pied imperial pigeon, the Torres Strait pigeon or the Torresian imperial pigeon. Imperial pigeons are only found in southern Asia, Australia, New Guinea and the Pacific, a distribution from the Himalayas ("D. badia") to Tahiti in the South Pacific ("D. aurorare"). The greatest diversity of birds is in New Guinea. Imperial pigeons are strong fliers, are capable of flight over oceans, and have been successful in colonising islands and archipelagos. Australia has a poor representation of "Ducula" amongst its fauna, with only one species breeding on the mainland ("D. spilorrhoa"). There is no clear explanation why more species