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Fwd: Re: fossil varanoids



Forwarding Michael Balsai's reply to my inquiry about fossil varanoids:

>Date: Mon, 8 Dec 1997 13:54:04 -0500 (EST)
>To: "Larry Dunn" <larrydunn@hotmail.com>
>From: "Michael J. Balsai" <mbalsai@sas.upenn.edu>

>>I asked about the possibility that certain varanids may have been the
>>top predators during the Mesozoic in certain specialized environments
>>(on islands, etc.).  Is there anything in the fossil record to 
indicate
>>this?
>
>I try to think of varanids as those defined by Estes et al 1988, which 
is
>the Varanidae and consists of the crown groups _Varanus_ and 
_Lanthanotus_.
>I also prefer to think of the Cretaceous forms as in the Varanoidea (or
>varanoids). This could include mosasaurs by some people's thought (they 
are
>at least "platynotans" by most people's agreement). Some include 
necrosaurs
>in the Varanoidea and some do not. None of these terrestrial forms were
>gigantic, though I believe many preyed upon baby dinosaurs and their 
eggs.
>As far as specialized environments, remember how BAD the fossil record 
is
>(thus, no, not so far)! I am presently working on the redescription of 
a
>Mesozoic varanoid called _Paleosaniwa_ (as in the Guerney stamp) which 
was
>known only from fragments and scrap...until now. I got a specimen to 
study
>that may be about 60+% complete. I can assure you the stamp is rather a 
bit
>off (but then the fossil "type" is merely a thoracic vert). I estimate 
the
>size of this lizard to have been somewhere between 5 and 7 feet, like a
>typical Nile monitor, let's say.
>
>
>>I also asked if there were any Mesozoic varanids comparable to
>>Megalania prisca, or whether this creature was a Meganesian anomaly.
>
>Nothing that big, other than possibly mosasaurs.
>
>>
>>Someone replied that lizard workers consider M. prisca to just be part
>>of Varanus now.  Is this true?
>
>I have seen it argued both ways, but most, that I have seen argued 
against
>it being _Varanus_. Presently, from what I have read (I have not seen 
the
>specimens yet), I would say no as well. Anyway, I believe it is merely 
a
>matte rof time before _Varanus_ gets broken up into several genera. 
Many
>consider the pygmy sized clade from Australia and surrounding islands 
to be
>an off shoot evolution from the main branch and I sometimes see them 
called
>the "Odatria" group.
>
>Mike Balsai


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