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Re: The Papers That Ate Cincinnati

Mike Keesey wrote:

Only if _O. hoazin_ goes extinct before giving rise to other species....

I think the point at which the hoatzin has given rise to other species, us _Homo sapiens_ would be long gone. :-(

Not true:
"Let C be the clade consisting of _Opisthocomus hoazin_ and all
descendants thereof. _Opisthocomiformes_ is defined as the first
ancestor of _O. hoazin_ (and hence of C) which is not also ancestral to any extant organism outside of C, and all of that first ancestor's descendants."

OK, that should work quite well for _Opisthocomus_. Opisthocomiformes would effectively be the same as Panopisthocomiformes.

The only potential problem (and it may not be much of a problem, except maybe in an aesthetic sense) is if all bird 'orders' are defined in such a way. For example, what would happen if the hoatzin is suddenly found to be nested inside another bird 'order' (like Cuculiformes)?

More specifically, what if a new fossil turns up that resolves _Opisthocomus_ as the sister taxon to Musophagidae, but _Musophagus_ is defined to be inside Cuculiformes? If Cuculiformes is defined as the clade containing the first ancestor of _Cuculus_ and _Musophagus_ and all its descendents, but which cannot include any extant bird outside of the _Cuculus_-_Musophagus_ clade, then Opisthocomiformes would be inside Cuculiformes.

My concern is that with modern bird phylogeny being in flux, certain traditional 'orders' may emerge as paraphyletic (some already have) and therefore contain other bird 'orders'. I have nothing against this per se, since ranks (such as 'orders') are arbitrary anyway. But it could all get very 'messy' - as I said, an aesthetic problem, not a substantive one. One solution is to junk the "-iformes" suffix altogether, and abolish all the baggage of the Linnaean ordinal classification of birds.



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