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Re: Kritosaurus?



George wrote:
>Go argue the point with Spencer Lucas; he'll give you something to chew on. 
>He's one of the authors of the Anasazisaurus/Naashoibitosaurus paper, and it 
>is essentially their argument that I presented.
        Go argue the point with Jack Horner (who is, as we all know, a bit
more involved with hadrosaurs than Dr. Lucas is). Since you do not wish to
argue Hunt and Lucas' point for them, may I ask why you choose to accept
their point over Horner's?

><< >distinguish the genus from Hadrosaurus,
>         Rather difficult, wouldn't you say, considering the limited
> documention of skull material in that genus? >>
>
>Baird and Horner once (1977) synonymized Kritosaurus with Hadrosaurus, 
>something you seem to have overlooked.
        No, I didn't overlook it at all. The question was whether
Kritosaurus could be differentiated from Hadrosaurus. I chose to accept your
(very very strict) approach to this sort of question... since the TYPES of
these two genera lack (dcoumented) overlapping parts (other than teeth), it
is naturally impossible to distinguish the two.

>On the basis of postcrania referred to Kritosaurus.
        Although I have still not been able to dig up Baird and Horner, I
should point out that much of the referred material upon which argumentation
of this synonomy has been based in other works is actually "Gryposaurus"
material from Canada, not Kritosaurus from the San Juan Basin.

Darryl Jones wrote:

>The sign says Kritosaurus incurvimanus and there are no quotation marks.  I
>was confused, however, by the fact that a cast of this specimen is on
>display at the Tyrrell as Gryposaurus notibilis and there is another
>specimen there (not nearly as complete) labelled Kritosaurus incurvimanus.
        I checked the RTMP webpage. The cast does indeed appear to be of the
type of Kritosaurus "incurvimanus," which Horner has referred to
Gryposaurus. The other specimen appears to lack a head, and may have been
referred to Kritosaurus long ago and may simply not have been updated to the
taxonomy accepted elsewhere in the displays.
        Remember that the people writing the text blurbs at museums are not
always scientists. Sometimes they are just trying to do the best they can,
and don't have the time to look up everything, much less the intuition to
guess if something is wrong. For that matter, it is often difficult even for
paleontologists to judge which of several taxonomic oppinions is most
appropriate for a group they themselves are not so familiar with.
        On the other hand, it may simply have an "in-curvy" manus.

George wrote:
>Some people think the species "Gryposaurus" 
>incurvimanus belongs to a distinct hadrosaur genus,
        Some people appear to be of the opinion that genera are like
recta... every species has one. :)

>as yet undescribed.
        Who does? This is very much news to me! On what basis was this
suggestion made?

David Krentz wrote:
>Sigh... I guess I'll just have to call my sculpture "gryposaur".
        Why not "kritosaur?"

Jaime Headden wrote:
>   Based largely on variation of the nasal bones
> relative to the rest of the skull, in both taxa.
        Suggested as ontogenetic by Horner in 1993.

>*N. ostromI* does appear to have a narrow occiput in dorsal aspect,
        Also possible ontogenetic.

>with squamosals flaring laterally, 
        Beware, some of the back part of that skull appears to be incomplete
(e.g. where are the exoccipitals/opisthotics). 

>and *A. horneri* with _very_ large supraorbital fenestrae,
        Again, possibly ontogenetic.

        Bear in mind that the one skull is from a significantly larger
animal than the other. The greatest differences are, as Jaime points out,
largely confined to the nasal hump. This is indeed suspiciously like the
condition in lambeosaurs. Of course, you never know, one of them may have
had a bright red hump with purple polka-dots, and the other an erect skin
frill sticking out sideways so it could glide from tree to tree and... oh,
yeah, this is supposed to be science...

        Wagner


--------------------------------------------------------------------------------
     Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
  "Why do I sense we've picked up another pathetic lifeform?" - Obi-Wan Kenobi