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Re: feathers & metabolism
(By popular demand, re-posted in plain text .)
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)
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
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 H Brush
92 High Street
Mystic, CT. 06355