Re: Gregory S. Paul on Confuciusornis

[Mike Habib <habib@jhmi.edu>]

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.

Cheers,

--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
habib@jhmi.edu