[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Re.: If Dinosaurs Could Fly and an old 'axiom'



At 01:34 PM 1/20/98 -0500, Ray Stanford wrote:
>Could be I'm missing something in all this, 'Which came first, the down or
the (flight) feathers?' controversy; but as a simple neophyte in all this,
it seems to me certain persons have forgotten a long-held axiom of
comparative anatomy:  ONTOGENY RECAPITULATES PHYLOGENY.

Well, Haeckel's Biogenic Law (shown in caps above) does turn out to be an
oversimplification, in that new stages or transformations can be inserted
anywhere in development (including the embryo), but Stanford brings up an
interesting point.

To the developmental biologists out there: what does a feather look like
during "plumagogenesis" or whatever it would be called (feathery equivalent
to odontogenesis)?  Do feathers begin structurally during development as a
spike which sends out shoots, which themselves send out shoots, etc.?  Do
feathers begin developmentally as a flat plate with a central shaft, with
material removed from the plate to form the feather substructures?
Inquiring, bone-biased minds want to know!

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661