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Re: the Horner interview - "fluffy" T. Rex??



dale mcinnes <wdm1949@hotmail.com> wrote:

> I would also say that too much is placed on "shedding" integument for
> endotherms for thermoregulation ... particularly feathered ones. Retention
> of feathers would "seem" to work a whole lot better. Direct hot sunlight
> reaching the naked skin directly I think wouldn't necessarily cool
> off an archosaurian endotherm but actually heat it up. A strong breeze might
> suffice in any case. Nature isn't going to try to do something very complex
> in order to provide a solution to a simple problem.


I think this is a neat hypothesis - having feathers (or arrangement of
feathers) specialized for cooling the animal.  On balance though, I
see no compelling reason why large dinosaurs (including large
theropods) simply didn't do what many large mammals do, and get rid of
most of their surface insulation.  Having said that, for many large
theropods there may have been no need to lose their extensive plumage
- like _Yutyrannus_.  But _Tyrannosaurus_ might have pared back its
protofeathery integument to a fairly sparse distribution over the
body.

Other structures in theropods might have been used to help shed heat -
crests and sails and so forth.


> So feathers to be retained
> would have to provide solutions to a myriad of problems [communication/
> toxic waste removal/ thermoregulation and so on].


Yes, feathers are extremely versatile even outside of flight-related
functions.  For example, there is some evidence that ostriches use
their wings in terrestrial/cursorial locomotion, especially to
increase stability and maneuverability when running.

http://www.sciencedaily.com/releases/2010/06/100630213614.htm

I haven't seen a formal publication yet (this work could have huge
ramifications for the origin of flight in theropods).  But it suggests
that the feathers of ostriches are retained for locomotory advantage,
as well as insulation, display, etc.

Feathers may indeed provide solution for a myriad of problems; but
they introduce problems of their own.  Feathers require extensive
maintenance and grooming.  Plus they are prone to infestation by
arthropod parasites that specifically target hair and feathers.







Cheers
Tim