the large reptile tree (LRT, 1118 taxa) nested the toucan, Pteroglossus, between the stink bird, Opisthocomus, and the parrot Ara + the giant parrots, Dinornis and Gastornis. That seemed reasonable. They are all frugivores and the nostril is high on parrots and toucans. However, with the addition of two taxa (Figs 2-5), and the reexamination of several others (remember, I’m new to birds) toucans moved from parrots to between crows and ducks (Fig. 4).
the hornbill, Buceros (Figs. 2,3) is added to the LRT. Traditionally hornbills and toucans do not nest together. All similarities have long been considered convergent. Here, in the LRT, toucans and hornbills do nest together. Very few traits distinguish the two in the LRT.
toucans are New World hornbills and/or hornbills are Old World toucans. So far… Remember all hypotheses of relationships can be trumped with better and more data.
Pteroglossus aracari (Linneaus 1758) is the extant black-necked aracari, a type of toucan. Toucans are restricted to the New World. Like the parrot, the bill is deep. Unlike the parrot, the nares are dorsal. Like the parrot pedal digit 4 is reversed. Wikipedia reports that toucans are related to woodpeckers. Here toucans are related to hornbills between stink birds and parrots. Like hornbills, toucans nest in tree hollows and are omnivores.
Buceros hydrocorax (Linneaus 1758) is the extant rufous hornbill. Hornbills are restricted to the Old World. Most studies find toucans and hornbills unrelated, similar only by convergence. The present study finds they are sister taxa. Nearly every trait in these two is identical to the other. The separation of toucans and hornbills had to happen by the Albian (Latest Early Cretaceous, 100 mya) based on the distance between the two continents at that time and the fact that these taxa are not long distance flyers.
The Piciformes question
Wikipedia , representing traditional systematics and taxonomy, nests toucans and barbets with woodpeckers, like Melanerpes, which nests here (Fig. 4) between swifts like Hirundo and dippers with Cinclus, all insect eaters, not frugivores. The LRT recovers a nearly completely different tree topology.
Psilopogon pyrolophus (S. Müller 1836; 28 cm in length; SE Asia) is the extant fire-tufted barbet. This frugivore resides at the base of toucans + hornbills and it also uses tree cavities to nest and raise chicks in.
Of added interest,
hornbills are restricted to the Old World, from Africa to Asia. Toucans are restricted to the New World. Since they shared a last common ancestor similar to both, the two clades must have separated when the continents separated, in the Albian (latest Early Cretaceous, 100 mya; Fig. 6). If true, this supports a growing realization that Neoaves did not radiate after the Cretaceous, but deep within that time period. Jungle taxa do not generally fossilize well. Even so, confirmation will be big news. Smaller barbets are found world wide.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Müller S 1836. Reizen en onderzoekingen in den Indischen archipel, gedaan op last der Nederlandsche Indische regering, tusschen de jaren 1828 en 1836, 1857