RE: The mystery of the furcula

["Tracy L. Ford" <dino.hunter@home.com>]

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Williams, Tim
Sent: Thursday, January 24, 2002 8:33 AM
To: 'dinosaur@usc.edu'
Subject: RE: The mystery of the furcula


George wrote:

>The furcula carries a lot of weight in theropod systematics,

Who says?

You're making a bold assumption here, which you can't possibly back up.
Heck, ornithologists to this day are still debating what the furcula is
actually used for.  And even if someone is absolutely certain what it is
used for in birds, it doesn't automatically tell you what the original
function of the furcula was. <<

Ok, first off, I'd like to know who where argueing with. Are you an adult or
teenager? This will determine the amount that I will debate with.

Second, as already mentioned, HELL YES we know what the fercula is used for.
In FACT it was do to paleontology that it was finally nailed down.
Jenkins, F. A,. Jr., Goslow G. E. Jr., and Dial K. P., 1987, Mechanics of an
avian wing: The wishbone is a spring: Journal of Vertebrate Paleontology, v.
7, supplement to n. 3, Abstracts of Papers, Forty-Seventh Annual Meeting,
Society of Vertebrate Paleontology, The University of Arizona, Tuscon,
Arizona, October 22-24, p. 19a.
Jenkins, F. A,. Jr., Goslow G. E. Jr., and Dial K. P., 1989, Evolution of
the Avian Shoulder Joint: Journal of Vertebrate Paleontology, v. 9,
supplement to n. 3, Abstracts of papers, Forthy-Ninth Annual Meeting,
Society of Vertebrate Paleontology, Vertebrate Paleontology Laboratory, The
University of Texas, Austin, Texas, November 2-4, p. 27A.

I was there for the talk (Wow, was it that long ago?)

>>The furcula (fused clavicles) is found in some theropods and not others,
and
even _Longisquama_ has something that looks like a furcula.  And if you're
going to tell me that a furcula is an essential component of flight, then
I'll point you in the direction of a few parrots that lack one.  They fly
very well too.<<

Good, but  I think the point is theropod researches use this, so I guess
they are all wrong!


Tracy Ford wrote:

>> But it illustrates the point that we shouldn't pick and choose our
>characters - unless we have damn good evidence
>that they're developmentally or functionally linked.<<

>But this happens all the TIME!

>>I meant (and I think my post made this very clear) that I was referring to
the subjective culling of character sets.  In other words, "The distribution
of this character is screwing up my pre-conceived phylogeny.  So out it
goes!"  E.g. George thinks that the furcula is of paramount importance in
theropod phylogeny: but his cladograms are not telling him this, he is
telling his cladograms.<<

Not only George, but Holtz, Paul, Norrell, etc. I guess they're all wrong.

And back to sauropods...

>NO, no, no. This assumes that all sauropods ARE titanosaurs and they go
>from there.  Nemgetosaurs are Diplodocids, Brachiosaurs are Brachosaurs,
>Opisthocoelicauda is a Camarasaurid, and Titanosaurs are Titanosaurs.
>Nature is very diverse and people need to understand that and not have
>tunnel vision with cladagrams.

I stated that the vast majority of LK sauropods belong to a monophyletic
group, the Titanosauriformes.  This embraces a great deal of diversity.
Chopping this clade up into smaller "families" in another context doesn't
alter this one iota.  Similarly, discussing tyrannosaurids, dromaeosaurids,
birds and therizinosaurids under the umbrella of "Maniraptorifomes" doesn't
deny the diversity of this group. <<

Ok, this brings up something I've been wanting to ask. IS there another
group of animals that have such a wide diversity of teeth? I.e. spade like
teeth to pencil like teeth. I'm talking about a small group, possibly order
and below.



Tracy L. Ford
P. O. Box 1171
Poway Ca  92074