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Re: Masso embryos disc./back to pteros



David Peters (davidrpeters@earthlink.net) wrote:

<I would have to disagree on the _degree_ of cuteness factor when dealing with
non archosaurs.>

  I hope no one's going to try to debate a criterion for cuteness, one of the
most subjective perspectives known to man? I listed features related to the
huge-headed, large-eyedness of hatchlings/embryos, and if you look back into
vertebrate history you will find these very self same features are incredibly
prevalent. This was the basis of my statement.

<And with regards to pterosaurs, I bow to Luis Chiappe who says (and
illustrates):

 "This specimen is indistinguishable from both juvenile and mature specimens of
Pterodaustro ? with its long, slender snout and evidence of filament-like
mandibular dentition.">

  This is good for *Pterodaustro* and, as identified, shows exception to a
rule. Show me prevalence of a "non-rule" in other vert groups aside from a
pterosaur or two? Note that several exceptional animals with long snouts such
as gharials and cranes have short snouts as juveniles. Chiappe's subjective
decision in indistinguishability is, as has been stated before, largely
unquantified. This doesn't invalidate "juvenile features" as has been noted
before. Prove me wrong by invalidating the features I noted.

  Incidentally, the *Massospondylus* embryos look rather like lizards to me,
with not exceptionally short but deep snouts, and actually remind me of "Baby
Louie", proposed as a therizinosauroid. This is in contrast to the Auca Mahuevo
sauropod snouts or embryonic birds, but since the sauropod skulls show clear
lachrymal and jugal anatomy of adults, there is differentiation from
homogeneity among sauropodomorphan embryos. The more triangular skulls of
theropod embryos and the curve-snouted croc embryos are in stark contrast in
archosaurs.

  Cheers,

Jaime A. Headden

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

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