Re: Notarium question

["Jaime A. Headden" <qilongia@yahoo.com>]

David Peters (davidrpeters@earthlink.net) wrote:

<The pterosaur notarium articulation is a new structure, that is, one not
present on Ichthyostega. I'm trying to think of other such examples in
tetrapods, but I'm coming up almost blank.

1. That funny new bone on top of the dorsal hump on Megalancosaurus.>

  Not sure this should be counted, or at least only with great
reservations; the fusion of the distal ends of the neural spines of the
second and third dorsals occurs only in *Megalancosaurus* among
drepanosaurids, and only in the neural spines.

<2. ???>

  A functional equivalent occurs in other vertebrates where the vertebrae
are not fused but are rendered virtually immobile, as in glyptodontids and
other large xenarthrans, and birds; the vertebrae are fused into a single
unit in turtles, as well, but this is the entire dorsal series through to
the sacrum, so not sure if its analogous.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

__________________________________
Do you Yahoo!?
Yahoo! SiteBuilder - Free, easy-to-use web site design software
http://sitebuilder.yahoo.com