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Re: bird scapulae query



"Bakker 86' said dinosaurs did not moved their scapulae in the manner
of quadrupedal dinosaurs, and this may be true; such a mammalian
motion does not appear to be present in crocodilians and birds."

Before this goes too far, I wanted to point out that x-ray videos show that extant crocodilians in fact have quite a bit of scapular rotation during locomotion (contrary to the traditional assumption). It also confirms that birds do not. Qualitatively it looks like the center of rotation in croc scapulae is somewhat lower than in quadrupedal mammals.

Cheers,

Scott


Scott Hartman Science Director Wyoming Dinosaur Center 110 Carter Ranch Rd. Thermopolis, WY 82443 (800) 455-3466 ext. 230 Cell: (307) 921-8333

www.skeletaldrawing.com

-----Original Message-----
From: Augusto Haro <augustoharo@gmail.com>
To: davidpeters@att.net
Cc: DML List <dinosaur@usc.edu>
Sent: Mon, 1 Jun 2009 9:21 am
Subject: Re: bird scapulae query






Apparently not, although the articulation between scapula and coracoid is not very rigid in at least some birds I saw. The coracoid is unmovably attached to the sternum, which moves in the sagittal plane with ventilation, and this likely makes the scapula move also. These movements are coordinated with flapping during flight, as far as I remember... During terrestrial locomotion, they would be produced by the respiratory motion of the ribs.

Bakker 86' said dinosaurs did not moved their scapulae in the manner
of quadrupedal dinosaurs, and this may be true; such a mammalian
motion does not appear to be present in crocodilians and birds.

2009/6/1 David Peters <davidpeters@att.net>:
Do the scapulae of birds move along the ribcage during locomotion?

If not, and they are more or less locked, at what node did this occur?

David Peters
davidpeters@att.net
after June 6:
davidrpeters@charter.net