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Re: Thermogenic muscle hypothesis for origin of birds




My initial impression is that this is a streeeeeeeee-tch...

To put it mildly.

And ignores possible theropod/avian relationships. 

That said, I have only read the abstract...

What prompted me to post a comment onlist, however - the abstract seems to 
propose that changes in egg shape/size select for altered morphology in the 
subsequent adult - and this is a new idea to me, and one that implies potential 
for abrupt changes... as they say.

Is it indeed a novel idea? Or did I just miss it sometime in the last century?  

------------------------------
On Thu, Apr 4, 2013 11:58 AM EDT Ben Creisler wrote:

>From: Ben Creisler
>bcreisler@gmail.com
>
>
>A new online paper:
>
>
>Stuart A. Newman, Nadezhda V. Mezentseva & Alexander V. Badyaev (2013)
>Gene loss, thermogenesis, and the origin of birds.
>Annals of the New York Academy of Sciences (advance online publication)
>DOI: 10.1111/nyas.12090
>http://onlinelibrary.wiley.com/doi/10.1111/nyas.12090/abstract
>
>Compared to related taxa, birds have exceptionally enlarged and
>diversified skeletal muscles, features that are closely associated
>with skeletal diversification and are commonly explained by a
>diversity of avian ecological niches and locomotion types. The
>thermogenic muscle hypothesis (TMH) for the origin of birds proposes
>that such muscle hyperplasia and the associated skeletal innovations
>are instead the consequence of the avian clade originating from an
>ancestral population that underwent several successive episodes of
>loss of genes associated with thermogenesis, myogenesis, and
>skeletogenesis. Direct bird ancestors met this challenge with a
>combination of behavioral strategies (e.g., brooding of nestlings) and
>acquisition of a variety of adaptations for enhanced nonshivering
>thermogenesis in skeletal muscle. The latter include specific
>biochemical alterations promoting muscle heat generation and dramatic
>expansion of thigh and breast muscle mass. The TMH proposes that such
>muscle hyperplasia facilitated bipedality, freeing upper limbs for new
>functions (e.g., flight, swimming), and, by altering the mechanical
>environment of embryonic development, generated skeletal novelties,
>sometimes abruptly, that became distinctive features of the avian body
>plan.