re: Tanystropheus egg question

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

David Peters (davidrpeters@earthlink.net) wrote:

<Tanystropheus, even at half of a's neck length, is a poor candidate for
an egg, but okay for an amniotic sac.>

  I don't see why a really long neck should be a prevention for being
egg-born given that extremely long vertebral columns can still be curled
up inside an egg, as in snakes, and adding hypothetical legs to the snake
bauplän would not interfere in the typical ovoid egg design, nor prevent
the idea of a hard egg. If the same body form can be encapsulated in an
amniotic sac, then it may just as easily be so in a calcified shell
_around_ the same amniotic sac.

<Multi-cusped teeth, big eyes and a short snout are also found in basal
pterosaurs, longisquama, langobardisaurus, and other prolacertiforms of
similar size. The big Tanys are definitely the oddballs.>

  To my knowledge, the impressions of the teeth in *Longisquama* are so
small and the granulation of the slab so large that determination of
multiple cusps would be extremely difficult to support. After seeing a
cast of the holotype specimen in person, I am at once amazed at how truly
tiny this thing is; the animal on a whole is smaller than a newborn
kitten, and the granulation very distinct, especially above the preserved
skeletal elements, where anything seen seems to be more or less in the eye
of the beholder. Let's also note that large orbits occur in anurognathids,
and that paedomorphosism is possible here, and that basal pterosaurs will
have similar designs, orbit to skull ratios caried on with
*Rhamphorhynchus,* as well as -- and especially so -- in *Sordes.* This is
a paedomorphic trend, one would think, but perhaps not indicative of a
trend linking the short-armed, long-legged quadrupedal prolacertiforms
with the short-legged, long-armed, volant and semi-quadrupedal pterosaurs,
which despite extensive recovery of Triassic prolacertiforms and basal
archosauromorphans, still fail to yield an earlier, semi-winged or
wingless pseudo-pterosaur.

  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)


                
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