from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A crested brownish bird (Opisthocomus hoazin) of tropical South America whose young have claws on the first and second digits of the wings.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A bird, Opisthocomus hoazin, with claws on the wing fingers of the juvenile and an enlarged crop used as a rumen.
from the GNU version of the Collaborative International Dictionary of English
- n. Same as hoazin.
from The Century Dictionary and Cyclopedia
- n. Same as hoactzin.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. crested ill-smelling South American bird whose young have claws on the first and second digits of the wings
The idea that the hoatzin is not close to seriemas or turacos, but is in fact a member of a hitherto-overlooked metavian clade at the base of Neoaves is an exciting one, mostly because it would make this bird strongly convergent on the coronavian turacos.
Even if the hoatzin is not one of them, cuckoos are quite interesting.
More taxa, more characters: the hoatzin problem is still unresolved.
Darren Naish: Tetrapod Zoology: Goodbye, my giant predatory, cursorial, flightless hoatzin
Based – it has to be said – on just a handful of detailed morphological characters, combined with some inference based on biogeography and superficial similarity, the South American landbird group theory suggests the following: that there might be a hoatzin-cariamaen clade, probably persisting as relicts in South America but more widespread during the early Cenozoic.
Worth noting is that, while there are two fossil hoatzins, neither of them preserve enough information to tell us anything useful about hoatzin affinities, or about the way of life of the fossil forms.
What do other studies have to say about the affinities of the hoatzin?
Sibley & Ahlquist (1973) concluded that the hoatzin was not just closely related to cuckoos, but actually deeply nested within Cuculidae.
Phylogenetic relationships of the enigmatic hoatzin (Opisthocomus hoazin) resolved using mitochondrial and nuclear gene sequences.
Most usually considered close to either gamebirds or cuckoos (in fact, when first described in 1776 the hoatzin was classified as a species of Phasianus), hoatzins have also been allied over the years with turacos, rails, hornbills, sandgrouse and pigeons.