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Re: Endothermy, UCP1 gene deletion, and the origin of birds



In his new paper Stuart A. Newman offers an interesting, if unclearly stated, 
hypothesis of bird origins. He proposes that it could have occurred due to the 
loss of the mitochondrial gene UCP1, then the subsequent development of 
compensatory muscle hyperplasia that allowed the ancestors of birds to regain 
endothermy. He suggests that the pectoral and pelvic muscles enlarged in order 
to generate heat, and that the skeleton compensated during embryonic 
development by enlarging, producing a robust sternum and pectoral girdle, and 
holding the femur in a  horizontal posture with  a reduced degree of freedom. 

Newman's paper does not reflect the current body of knowledge of diapsid 
paleontology in general and avian origins in particular, but in this open 
letter he implicitly asks the experts if his insight can be helpful to them.

 Newman would have to be criticized if this were a formal paper. The weaknesses 
include the failure to substantiate anatomical claims, to clearly state a 
hypothesis, and a misunderstanding of the differential extinction at the end of 
the Cretaceous. But the paper is offered as an open letter, in a journal 
dedicated to open discussion and hypothetical thinking, and should be 
approached as such.

 The strength of the paper is that it offers a novel genetic and physiological 
explanation for the acquisition of a suite of avian characters, such as 
enlarged pectoral musculature and horizontal femoral posture. It also provides 
developmental insights that lend credibility to this possibility. Therefore 
Newman provides an alternative and / or supplement to adaptationist 
explanations of bird origins.

In my opinion Newman's insight could be incorporated into a phylogenetic 
context and made into a  strong hypothesis. That hypothesis could be tested and 
I'd be fascinated to see the results.

-Jason

On Aug 15, 2011, at 11:08 AM, Jason Brougham wrote:

> Dr. Newman's paper is finally available. His hypothesis is way outside the 
> norm in dinosaur debates, and I'm still trying to grasp it.
> 
> Stuart A. Newman. Thermogenesis, muscle hyperplasia, and the origin of birds. 
> BioEssays, 2011; DOI:10.1002/bies.201100061
> 
> http://onlinelibrary.wiley.com/doi/10.1002/bies.201100061/abstract
> 
> Jason Brougham
> Senior Principal Preparator
> American Museum of Natural History
> jaseb@amnh.org
> (212) 496 3544
> 
> 

Jason Brougham
Senior Principal Preparator
American Museum of Natural History
jaseb@amnh.org
(212) 496 3544