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Re: Viva Neornithine Birds!



BTW, doesn't "viva" have a distinct plural...?

Would one not expect even (or especially?) in a
reasonably well-calibrated model the "molecular"
divergences (which starts with cessation of
significant gene flow between sister populations, i.e.
more often than not at the species level) to predate
the fossil one (which is based on distinct osteology,
which only can start some time *after* lineages *have
separated*)?

I've often seen that argument being made by molecular phylogeneticists. Frankly, it looks like those people use cladistics without understanding how it works, and/or mightily confuse phylogeny and nomenclature (which is, BTW, a very common occurrence).


Suppose we find a Cretaceous fossil that's more closely related to the extant parrots than to the extant pigeons. (Whether it is a member of Psittaciformes then depends _only_ on the definition of the name Psittaciformes.) Where will a cladistic analysis put it?

If it shares any derived characters with the parrots but not the pigeons, it will be found as the sister-group of the latter. If it does not (because osteological autapomorphies of Psittaciformes had not yet evolved), we will find it in a trichotomy with Psittaciformes and Columbiformes.

We will _not_, however, find it to be _outside_ the parrot + pigeon clade. Why? Because it has the synapomorphies of parrots and pigeons. It must have them; they have by definition evolved before the parrot-pigeon split.

If no such apomorphies have evolved along the internode that separates the parrot-pigeon clade from its closest relative (or if they have evolved but have not been recognized by the authors of the analysis because they didn't have the patience of Livezey and Zusi), then the analysis will find a polytomy consisting of the parrots, the pigeons, the new fossil, and that closest relative.

Bluntly: no need to be special, you just need to be
lucky.

Yep.

and via Antarctica (and Africa?) to SAm,

Africa was the first to break off Gondwana, starting with its separation from Madagascar and Antarctica in the Jurassic and ending with the separation of Brazil and Nigeria some 105 to 100 Ma ago (latest Early Cretaceous). That's why Cracraft, assuming that ostriches and rheas are sister-groups and that their flightlessness is a synapomorphy, gets such incredibly old ages for Neornithes and most large clades therein.


it appears to me that what would need to be looked into
is the Late Cretaceous fossil record for
non-Neornithes from Australia or adjacent Antarctica
(which is IIRC all but non-existent).

The terrestrial fossil record of the Late Cretaceous of Australia is currently limited to a single dinosaur bone -- and it's not from a bird, but said to resemble a segnosaur (!!!) humerus most.


* That is to say, in the same family-level clade in
all probability, more likely than not even in the same
subfamily-level clade.

** In Linnean terms, a Charadriiformes order with
maybe 3-5 major lower-level clades, a "higher
waterbird" order which might (more probable methinks)
or might not have included the seabirds with (very
roughly) short of 10 families, and one or two (or
three?) "higher landbird" orders with between 2 and 10
families each, one of which would have included
"proto-Passeriformes" (which 65 mya were probably not
a distinct entity at higher than tribe level) - all
very crude estimates, and discounting minor ,
independent lineages (can't think of any surviving
ones really though that would have been distinct at
order level then. Perhaps buttonquails, if they are
not Charadriiformes but "intermediate" between these
and "higher waterbirds". But these are also centered
on the Wallacea-Indian Ocean region today).

Don't use ranks so much. You'll end up believing in them. :-)

Most all evidence indicates that Charadriiformes at
least were a) well distinct, b) fairly vigorously
radiating, and c) globally distributed 65 mya far more
likely than not.

Well, someone should put *Cimolopteryx* and friends into the new analysis.

And then this: though it proves nothing, it is very
interesting to take a globe model of K/P earth and
mentally run a needle from Chixculub through the exact
center. Where does it emerge again?

Somewhere off India?