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Re: Gregory S. Paul on Confuciusornis

True; that is technically not the correct way to explain the difference.  On 
the other hand, I knew immediately what he meant, as will most other 
biomechanicists, so I don't think it will be a critical typographical error.  
Your irritation is noted and understood, however.  Actually, I believe Paul 
also found the feather rachis to be thicker in Archaeopteryx than the authors 
suggest (have to go check that again), so he may indeed find a greater 
strength, as well - in which case the manuscript should mention both greater 
strength and lower relative loading from body weight.


--Mike H.

On Oct 15, 2010, at 9:38 AM, Mark Pauline wrote:

> Thanks Mike, but this says that the feather STRENGTH is "several times 
> stronger" 
> than that calculated by Nudds and Dyke. It doesn't say that the loading is 
> several times less. 
> This is a technical letter in a top quality science publication. The authors 
> have to be very precise and very clear in presenting their ideas. Moreover 
> their 
> methods and calculations must be repeatable.
> Mark
> ----- Original Message ----
> From: Mike Habib <habib@jhmi.edu>
> To: "markpauline@rocketmail.com" <markpauline@rocketmail.com>
> Cc: "dinosaur@usc.edu" <dinosaur@usc.edu>
> Sent: Thu, October 14, 2010 7:12:12 PM
> Subject: Re: Gregory S. Paul on Confuciusornis
> The mass does not change the feather strength itself, but alters the strength 
> relative to body weight, which is the key variable in question.  
> --Mike H.
> Sent from my iPhone
> On Oct 14, 2010, at 3:46 PM, Mark Pauline <markpauline@rocketmail.com> wrote:
>> In the new Science out this afternoon:
>> Comment on “Narrow Primary Feather
>> Rachises in Confuciusornis and
>> Archaeopteryx Suggest Poor
>> Flight Ability”
>> DOI: 10.1126/science.1192963
>> Science 330, 320-b (2010);
>> http://www.sciencemag.org/cgi/content/full/330/6002/320-b
>> I had two questions about Paul's text.
>> 1) "Nudds and Dyke (Reports, 14 May 2010, p. 887) reported that the primary 
>> features of the early birds Archaeopteryx and Confuciusornis were too weak 
>> to 
>> power flight"
>> What are these "primary features" that Paul describes? How do these features 
>> confer weakness on the animals in question?
>> 2) "the shallow-bodied basal bird was intermediate in mass to the 
>> Munich Archaeopteryx and the deep-bodied pigeon, so the feathers were a 
>> number 
>> of times stronger than calculated by Nudds and Dyke (Fig. 1, A to C)."
>> How does changing the mass make the feathers stronger or weaker? Isn't 
>> strength 
>> an inherent quality that depends on the structure of the feather?

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