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




From: "Mickey Mortimer" <Mickey_Mortimer111@msn.com>
Reply-To: Mickey_Mortimer111@msn.com
To: <dinosaur@usc.edu>
Subject: Re: How are columbiformes (doves and pigeons) related to psittaciformes?
Date: Mon, 10 May 2004 14:12:49 -0700

John Pourtless wrote-

> I would quite agree that assigning an isolated and rather fragmentary
lower
> jaw to crown orders is not particularly merited. Problems are after all
> legion in using fragmentary material to identify Cretaceous or even
Tertiary
> birds, which has been noted before (e.g., Olson 1985a) and marvelously
> demonstrated by the example of *Limnofregata azygosternon* (Olson 1977b).

That's science for you. If we waited until we were sure of something before
hypothesizing it, nothing would be known. Regarding Limnofregata, you're
referring to its recent reidentification as a sulid (Gulas-Wroblewski,
2003), right?

> As for the whole issue of pigeon/dove relationships...I find the papers
> cited by several of you most interesting to be sure, but am still cautious
> on the matter and would agree with Sibley & Ahlquist (1990) in stating
only
> that Columbiformes have no close living relatives, and that sandgrouse are
> not closely related thereto.

Sounds like a cop-out to me.  Something has to be their closest living
relative, regardless of how quantitatively close it is.  Pteroclids
(sandgrouse) were found to be their sister group in both recent large scale
phylogenetic analyses of neornithine orders, which looks like pretty good
evidence to me.  Mayr and Clarke (2003) found the relationship supported by
seven synapomorphies-
- Os ectethmoidale, greatly expanded and more or less inflated, plate-like,
with dorsal margin largely fused
with os frontale.
- Vomers vestigial or absent.
-  Several thoracic vertebrae fused to a notarium.
- Humerus short and stocky with crista deltopectoralis strongly protruding
and triangular.
- Humerus, tuberculum dorsale greatly elongated proximodistally.
- Femur, crista trochanteris markedly projected cranially.
- Musculus flexor perforans et perforatus digiti III, vinculum.

Mickey Mortimer


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. 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.

As for pteroclids and doves/pigeons...I pulled out Mayr & Clarke (2003), though it was most kind of you to provide the synapomorphies they listed for this grouping and even dug out Cracraft's godforsaken 1981 paper. I will agree that there is good evidence for a pteroclid/columbiform nexus, and retract my comment to the contrary.

JGK

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