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RE: Dinosaur Revolution Review

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of Scott Hartman
> Sent: Thursday, September 15, 2011 12:55 PM
> To: Jura
> Cc: dinosaur@usc.edu
> Subject: Re: Dinosaur Revolution Review
> I've often disagreed with how Jason applies some of the 
> evo-devo findings to feather distribution, but I want to go 
> on the record as agreeing with him in part: there really 
> isn't a known mechanism for dermal types to shift after 
> ovo/utero within an individual's lifetime.
>  That's not to say I don't believe in the possibility of 
> fuzzy juveniles, but they would have to work within known 
> developmental mechanisms.

[snipped a lot of good stuff: go back to the original to read]

It think the error here is the appropriate level at which to look at the 
"feathers-back-to-scale" issue. Almost certainly it is
impossible to "go back" **at the follicle level**: once a follicle is dedicated 
to one of those modes, it is probably dedicate for
life (or simply turns off).

But we are dealiing with organisms here that in some cases increase their 
surface areas by many many many many orders of magnitude,
while scale size (for instance) increases at no where near that rate. Almost 
certainly there was the appearance of new follicles
during ontogeny: the developmental process in these has (so far as I know) not 
been explored in great detail.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661               

Faculty Director, Science & Global Change Program, College Park Scholars
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA