The hornbills and hops or hornbills (Bucerotiformes, also Bucerotes) are an order of birds to which four families of birds belong, which in older publications were mostly counted among the whackers (Coraciiformes). Hornbills and hops are found in southern and central parts of Europe, Asia, and sub-Saharan Africa. In total, the order includes 72 species.
Some authors did not recognize that hornbills belonged to the whackers and classified them in the monotypical bucerotiformes until recently . Today the hoopoes (Upupidae) and the tree hops ( Phoeniculidae) are put into order and the ground hornbills ( Bucorvus ) received the rank of a family, so that the Bucerotiformes today comprise four families. The close relationship of the four families is based on molecular biological studies. Morphologically they hardly differ from the rocket birds. In this way, the monophyly of the sackbill was preserved in relation to the woodpecker , which is located deep within a clade comprising sackbirds, hops and hornbills .
The Bucerotiformes are the sister group of a common taxon made up of rocket birds and woodpecker birds. The taxon formed by all three is the sister group of the Trogons.
Frank Gill and Minturn Wright: BIRDS OF THE WORLD Recommended English Names. Princeton University Press, 2006, ISBN 0713679042
Hackett et al .: A Phylogenomic Study of Birds Reveals Their Evolutionary History . Science 27 June 2008: Vol. 320. no. 5884, pp. 1763 - 1768 doi : 10.1126 / science.1157704
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