Re: feathers & metabolism

[MKIRKALDY@aol.com]

(By popular demand, re-posted in plain text  .)
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From: brushes2@juno.com
To:  DINOSAUR@usc.edu
Sent: 6/12/2011 10:18:27 A.M. Eastern Daylight Time
Subj:  feathers & metabolism

Jason Brougham wrote regarding dinosaur  feathers and plumages,
especially their visualization. I call attention  to:

Comp. Biochem. Physiol., 1965, Vol. 15, pp. 399 to 421. Pergamon  Press
Ltd. Printed in Great Britain
ENERGETICS, TEMPERATURE REGULATION  AND
CIRCULATION IN RESTING, ACTIVE AND DEFEATHERED
CALIFORNIA QUAIL,  LOPHORTYX CALIFORNICUS
ALAN H. BRUSH*
Department of Zoology, University of  California, Los Angeles
(Received 4 February 1965)
Abstract--
1. Lophortyx californicus is an obligate homeotherm and tolerates a marked  
hyperthermia with only slight adjustments of metabolic and heart rate.
2. The  unfeathered portions of the extremities provide an important 
accessory pathway  for heat dissipation at high Ta (ambient temperature) and 
for 
heat conservation  at low T a.
3. Conductivity values of the extremities can be used to  construct a model 
of the metabolism of defeathered birds.
4. Metabolic  adjustments of defeathered birds and of feathered, active 
birds at various  ambient temperatures are described in terms of thermal 
conductivity and oxygen  pulse.

This was a part of my dissertation work (UCLA, 1964) and  demonstrated 1)
the role of the bare parts of the legs in temperature  regulation and 2)
the adjustments in metabolism (oxygen consumption) and  circulation (heart
rate and cardiac output) in featherless birds. As  dinosaurs were becoming
more homeothermic and capable of maintaining a higher  body temperature,
several things would have been involved. Greater metabolic  heat
production (and oxygen consumption), increased insulation  (thermal
resistance provided by feathers), and finer regulation of cardiac  output
(to support metabolism and heat balance in homeothermy).

These  are still the closest measurement of the physiology of a common
ancestor in  the literature. 

Alan

Alan H Brush
brushes2@juno.com
92 High  Street
Mystic, CT. 06355
(860) 572-1717
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