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RE: Megalania question - DNA

One of the conclusions Molnar (2004) reached about _Megalania prisca_ is
that it is a species of _Varanus_, i.e. he sunk the genus. Nobody since
Fejervary, afaik, has argued for a phylogenetic position outside _Varanus_,
so it was about time this was done formally. 'Megalania' is a beautiful word
though, and I'm all for keeping it around as the 'common name' for _Varanus
priscus_ (Owen).  (Similarly, _Montypythonoides_ Smith & Plane, 1985
achieved wide name-recognition for a Miocene python from Riversleigh, which
turns out to be phylogenetically within the extant genus _Morelia_ Gray).

The original question was about most-recent age, presence in caves, and
potential for DNA recovery.  While the giant goanna does occur in cave
deposits (Wellington, NSW, and Naracoorte, SA; Reed & Hutchinson 2005), it
seems the climate, chemistry and relatively great age (mostly >>40ka) of
Australian Pleistocene deposits with megafauna makes the prospects for
ancient DNA pretty poor. There was discussion on this with Alan Cooper at
the 2005 CAVEPS in Naracoorte; I presume he's still looking, but as far as
the titles listed at http://www.adelaide.edu.au/acad/publications/ indicate,
there is still no Pleistocene DNA of any organism known in the whole

Molnar, R.E.  2004.  The long and honourable history of monitors and their
kin.  In E.R. Pianka, D.R. King and R.A. King (eds), Varanoid Lizards of the
World, 10-67.  Indiana University Press, Bloomington & Indianapolis. 

Reed, E.H., and M.N. Hutchinson.  2005.  First record of a giant varanid
(Megalania, Squamata) from the Pleistocene of Naracoorte, South Australia.
Memoirs of the Queensland Museum 51: 203-213.

Dr John D. Scanlon, FCD
Riversleigh Fossil Centre, Outback at Isa
"Get this $%#@* python off me!", said Tom laocoonically.

-----Original Message-----
From: Dann Pigdon [mailto:dannj@alphalink.com.au] 
Sent: 03 June, 2008 4:05 PM
To: dinosaur@usc.edu
Subject: Re: Megalania question - DNA

Jura writes: 

> Molnar also goes into great detail into the tail length problem, and how
widely ranging these results can be depending on length estimates. He
mentioned that if _Megalania prisca_ had a tail that was 2.3 times
bodylength, like in _V.varius_ then the largest specimen would have clocked
in around 7.9 meters. If, as Hecht suggested, the tail was half SVL, then
the largest individual would have been 5.2 meters.  
> However, since no living monitor shows a tail that is less than SVL, this
latter estimate is probably wrong. In the end Molnar assumed a tail length
that was equal to body length (like in oras), which resulted in a 7 meter

It'd be interesting to compare the proportion of total length the tail makes

up with total mass in a range of living varanids, to see whether there's a 
nice neat relationship (tails getting proportionally shorter as mass gets 
bigger, for instance). If there is a nice neat trend, then scaling up to 
Megalania-size might then result in a tail that is less than the 
snout-to-vent length. 

Of course in the absence of actual fossil material, it's still just another 
method of interpolation. 


Dann Pigdon
GIS / Archaeologist              http://geo_cities.com/dannsdinosaurs
Melbourne, Australia             http://heretichides.soffiles.com