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Re: New Ruben Paper

Not quite - the premise is that several adaptations of the avian hip and femur excursion allow the pelvic girdle and thigh musculature to help support the lower, lateral abdominal walls, which appears to provide resistance to collapse for the posterior abdominal air sacs in living birds. It's actually a neat finding, and not at all implausible. The problems don't hit until later in the discussion, at which point the authors make a number of poor assumptions, including (but not limited to): 1) lack of the modern-condition air sac expansion makes flight impossible; 2) lack of the modern-condition posterior air sac expansion means a flow-through lung was not present, and 3) the only way to support the posterior air sacs is with the pelvic condition seen in living neornithines.

I'd be curious to hear what the authors think of flight and respiration in pterosaurs.



Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280-0181 habib@jhmi.edu

On Jun 9, 2009, at 4:19 PM, Mark Hallett wrote:

As we always say, "wait for the paper", but is Ruben's entire premise actually based (on the the implication as I understand it from the SCIENCE DAILY article) that birds have inflexible or only potentially flexible knee joints? This is incorrect. --Mark

--- On Tue, 6/9/09, Mike Taylor <mike@indexdata.com> wrote:

From: Mike Taylor <mike@indexdata.com>
Subject: New Ruben Paper
To: Danvarner@aol.com
Cc: dinosaur@usc.edu
Date: Tuesday, June 9, 2009, 9:18 AM

From the article:

"Frankly, there's a lot of museum politics involved in this, a lot of careers committed to a particular point of view even if new scientific evidence raises questions," Ruben said.

*nods wisely*

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)_v__/\ "Don't you practise your alliteration on me!"
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