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Re: Furculae [sic]



Date: Tue, 19 Nov 1996 13:16:25 -0500
Reply-To: Dinogeorge@aol.com
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From: Dinogeorge@aol.com
To: mrowe@indiana.edu, cnedin@geology.adelaide.edu.au
Cc: Dinogeorge@aol.com
Subject: Re: Furculae [sic]

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----------------------- Message requiring your approval ----------------------
From: Dinogeorge@aol.com
Subject: Re: Furculae [sic]

In a message dated 96-11-19 12:19:28 EST, znc14@ttacs1.ttu.edu (Jonathan R.
Wagner) writes:

<< At 08:28 AM 11/19/96 +1030, George wrote:
 >_Segisaurus_ (but may be clavicles)
         The recent discovery of clavicles on the "Headless Wonder"
 allosauroid at DNM may cause some workers to rethink the theory that furcula
 are neomorphic.  Chure's JVP article (ref not available right now, sorry.
 im surprised you didn't mention it, George...) has some interesting things
 to say aout the Bryant and Russell paper George cites.  I realize that this
 would not fit as well into George's "BCF" theory, but even if avian furcula
 are clavicles, I'm sure it won't do irrepairable harm.>>

Chure & Madsen's article is

Chure, D. J. & Madsen, J. H., 1996. "On the presence of furculae in some
non-maniraptoran theropods," Journal of Vertebrate Paleontology 16(3):
573ñ577 [September 19, 1996].

It fits very nicely with BCF. I'm always glad to see avian, flight-related
features such as furculae in pre-maniraptoran theropods. But the furcula is
not a neomorph; it is the clavicles fused along the midline into a single
bone. The only thing neomorphic about it is the fusion. When birds become
flightless, the furcula shrinks along with the wings and keeled sternum,
separating into clavicles or, most often, disappearing entirely into
cartilage. This, of course, is also the reason furculae are seldom seen in
typical cursorial theropods...

And the "clavicles" on the "headless" DNM allosauroid, which is no longer
headless (skull found this summer with gamma-ray detectors), aren't
clavicles. Dan's photos of the specimen in situ clearly show a >furcula< atop
the scapulocoracoids. This inspired Dan to take another look at some
"gastralia" in Madsen's _Allosaurus_ monograph. The latter turned out to be
the _Allosaurus_ furculae redescribed in the reference above.

 >confirmed by Phil Currie). Not to mention _Longisquama_ and
_Archaeopteryx_.
         For clarity's sack, lets point out here that George is the only
 person I've ever heard who has, in this decade, seriously proposed that
 _Longisquama_ is potentially a dinosaur (although he doesn't spell it out
 like this, that's what he's saying, as here), or even potentially a close
 outgroup.  SO those of you who are about to write in asking about this, go
 back home, have a coke, pop some popcorn, watch a little tv.  Nothing has
 changed. >>

Hey--_Longisquama_ isn't just >potentially< a dinosaur. The furcula and the
elongate, featherlike ?scales place it within Theropodomorpha at the base of
Aves. It's more dinosaurian (i.e., diverged later from the dinosaurian common
ancestor) than _Apatosaurus_. I predict that if and when the hindquarters of
the creature (pelvis, hind legs, tail) are ever discovered, they'll turn out
to be surprisingly dinosaur-like: three sacral vertebrae, perforated
acetabulum, nearly erect hind limb with inturned femoral head, etc. There
will, however, still be five functional digits in the hind foot.

Just because others don't think so--YET--is no reason not to consider
_Longisquama_ a dinosaur. Look at the material, read the literature, study
the figures. Don't just take my word for it--but don't just take everybody
else's differing opinion, either.