Re: How are columbiformes (doves and pigeons) related to psittaciformes?

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

John Pourtless wrote-

> As it were, I am not familiar with the reidentification of *Limnofregata*
as
> a sulid and would not be terribly convinced of it, certainly not on your
> authority alone.

I wouldn't be convinced on my authority of pelecaniform phylogeny either.
Luckily for us, you'll note I included a reference to someone else's work in
my statement.  This would be Bonnie Gulas-Wroblewski
(http://www.fmnh.org/research_collections/pritzker_lab/pritzker/people/grad_
gulas.html), whose abstract I copy below.

Gulas-Wroblewski, B.E. 2003. Limnofregata: not a frigatebird anymore.
Journal of Vertebrate Paleontology. 23(3) 58A.
Limnofregata azygosternon, a fossil pelecaniform (Aves: Pelecaniformes) from
the
Green River Formation of Wyoming, has traditionally been cited as the oldest
occurrence of
the family Fregatidae, which includes the extant genus Fregata
(frigatebirds). However, a
cladistic analysis employing 153 morphological characters across eleven taxa
(nine extant
members of Pelecaniformes, two outgroup representatives, and the holotype of
Limnofregata)
places L. azygosternon as the sister-taxon to a clade containing the extant
Sula (boobies) and
Morus (gannets). This position is supported by the following synapomorphies:
1. extensive
papillae remigalis caudalis of the ulna absent or greatly reduced, 2. edge
of the bicipital surface
of the humerus does not reach over the sulcus ligamenti transverses, 3.
crista cnemialis
lateralis of the tibiotarsus slightly hooked. The relocation of this fossil
genus to the Sulidae, a
more derived clade within Pelecaniformes than Fregatidae, affects previous
molecular clock.
hypotheses of early neornithine radiation that used Limnofregata as a
calibration point.
Furthermore, the oldest occurrence of a fossil sulid is shifted back to the
early Eocene (53.5-
48.5 Ma), providing insight into the early diversification of one of the
basal orders within
Neornithes.

> The point I was referring to in bringing up *Limnofregata*
> is that as noted by Olson when he described it, there are portions of the
> skeleton that could be referred to any number of modern taxa or entirely
new
> taxa, thus indicating that one must use care in diagnosing fragmentary
> remains from Cretaceous or Tertiary birds (and indeed any vertebrates,
from
> any time).  What truly baffles me is where in my comments about this
> situation, I advocated waiting until we know everything conceivable about
a
> taxon to make any conclusions about it, as you have so magnanimously
implied
> on my behalf.  Looking at my writing what I distinctly see is the comment
> that one should not rush to press extraordinary claims that there were
> parrots darting round the Mesozoic forests on a poorly preserved scrap of
> jaw alone, as often such fragmentary remains are useless and of no value
in
> discerning the phylogeny of a group, which I would argue that the history
of
> paleontology as a whole, abundantly demonstrates.  There is a thing called
> responsible work, you know, as opposed to sensationalism, and I can think
of
> no better example than the Stidham paper from 1998.  Careful research and
> prudence would dictate conservativsm in pushing back the known range of an
> entire recent order of birds to the Cretaceous especially given the
> fragmentary nature of the finds in question, but this has hardly stopped
> Stidham or those who agree with him.

I think Gulas-Wroblewski's work demonstrates a different, but related,
point- Even given complete skeletons (as were available to Olson in 1977),
phylogenetic identification can be just as wrong as if the specimen were a
single element.  So if your wish is to postpone identification of specimens
until we "know enough" about the taxon to place it securely in a clade,
you'll have to wait until we know everything.  You can say a partial dentary
isn't enough to responsibly place a taxon, but how complete must a specimen
for us to be able to place it responsibly?  Apparently even a complete
specimen (the holotype of Limnofregata even has feather impressions) isn't
enough to place a taxon unambiguously.  So based only on completeness,
there's going to be no real dividing line between when it's appropriate to
refer a taxon to a clade, and when it's not.
Often fragmentary remains are "useless", and often they don't help determine
the phylogeny of a clade.  But there's more to paleontology than phylogeny
(*Jaime Headden drops dead upon noting I said this* :-) ).  Scraps of bone
can often increase the known spatiotemporal distribution of clades for
instance, as Stidham's parrot is reported to do.  Is Stidham's claim of
Maastrichtian loriines really extraordinary and lacking in careful research?
He seemed to have examined all other possibilities for the jaw and ruled
them out on morphological grounds.  Molecular evidence and the fossil record
are continuing to push back the emergence of many neornithine clades, so
that a Late Maastrichtian parrot doesn't seem so unlikely.  After all, the
history of paleontology has also demonstrated clades often have much greater
temporal ranges than we thought.  This latter fact diminishes the utility of
dismissing seemingly out of place remains as mimics of the clades they
resemble.  If we used such a philosophy, it would be quite subjective how
out of place a specimen must be to be removed from the taxon it appears to
belong to.  Better to work on a purely morphological basis, and treat all
specimens as equally likely to be anything.

Mickey Mortimer