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Re: Gnathosaurus question



Dave Peters (davidrpeters@earthlink.net) wrote:

<Gnathosaurus is well known for having a spoon-shaped rostrum. But the
dentary assigned to this genus does not appear to be spoon-shaped (see
Wellnhofer 1991). Am I missing something here?
  
This becomes important to Dr. Unwin's hypothesis linking Cearadactylus
atrox to Gnathosaurus cladistically, because he notes that Cearadactylus
has a spoon-shaped dentary, much wider than its not-so-spoon-shaped
rostrum.>

  Well, the argument is flawed, in my opinion. 1) The dentary may be
falsely assigned to *Gnathosaurus.* 2) The dentary, contra the upper
rostrum, may lack the mediolateral expansion, something seen in the
"spatula-"snouted croc *Terminonaris,* and to a limited degree in its
relative *Sarcosuchus,* so it is possible. To my knowledge, while
*Huanhepterus* has the downturned, expanded upper rostrum, the lower is
not expanded, as well. The modern spoonbill, *Platalea,* also lacks a more
distinct lower expansion than the upper jaw does.

=====
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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