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RE: Vestigial horse toes (short comment)

Concerning my comment on Napoleon's 3-toed horse:

The toes were not merely bumps on the side of the main toe, they appeared to
be about 3 or 4 inches (7-10 cm) long, protruding from each side of the main
toe.  They were not functional, since they appeared about 8-10 inches (20-25
cm) above the ground.  (This is based on a drawing of the horse that I have
seen).  I know that at least 2 of the horse's legs had these twos - I don't
remember if all 4 legs did.

As to whether these toes were "polydactyl-like" mutations - based on the
location of the toes, I think that these are genuine re-expressed genes, not
new mutations.

Allan Edels

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
K. Hunt
Sent: Saturday, August 26, 2000 12:16 PM
To: dinosaur@usc.edu
Subject: Re: Vestigial horse toes (short comment)

On Fri, 25 Aug 2000, Jarno Peschier wrote:
> > -----Original Message-----
> > From: Edels [mailto:edels@email.msn.com]
> > Sent: Friday, August 25, 2000 6:31 AM
> > To: Dinosaur Mailing List
> > Subject: RE: Electronicly published: why don't modern birds
> > have teeth?
> >
> > Stephen J. Gould has a book titled "Hen's Teeth and Horse's
> > Toes", which contains an essay with the same name.  I
> > believe he also describes Napoleon's 3-toed horse (The two
> > extra toes were definitely vestigial - they didn't even
> > touch the ground).
> As anyone who has ever cleaned the hooves of a horse knows basically every
> horse living today has some vestigial toes left, high up on the leg. I
> know what they're called in English, but in Dutch they're called the
> "zwilwratten". But the ones on old Bonaparte's horse where probably
> further down the leg and looked actually like toes, much like that
> well-known "What's-their-name-hippus" _Equus_ ancestor that had toes like
> that.
> Met vriendelijke groeten,
> Jarno Peschier, postbus@jarno.demon.nl/jarnop@ccs.nl

They are called "chestnuts" in English. But I don't know if they're really
homologous to side toes or if that is just a stable legend. As far as I
know, chestnuts are epidermal and are not connected to any underlying
bones or muscles. I suppose they could just be some sort of leg gland
(similar to the leg glands on many deer) not related to toes.  Anyone have
more information?
  PS for anyone who hasn't seen chestnuts, they're callosities on the
inside of the horse's leg; one on each leg; usually oval in cross-section,
about an inch across, smaller on the hind leg. They grow continuously from
the base and the outer surface flakes off. Sometimes they have to be
  - Kathleen  hunt@u.washington.edu