CRETACEOUS VARANIDS

[darren.naish@port.ac.uk]

First off, amusing names.. the Aussie snake _Montypythonoides_. I 
don't have the literature with me, but I recall that this one is now 
thought to be a synonym of _Wonambi naracoortensis_ (am I right 
Paul?). _Wonambi_ is one of the enormous madtsoiid snakes. They 
apparently grew to 7-8 m or more and could have weighed over 800 kg. 
I suspect madtsoiids were semiaquatic or amphibious, like giant 
living _Eunectes_ (anacondas) and _Acrochordus_ (wart snakes / file 
snakes / elephant trunk snakes), but there have been suggestions that 
they were cave-dwelling climbers. Madtsoiids are no longer thought to 
be close relatives of living pythons and boas, incidentally, and seem 
instead to be an ultra-primitive sister-group to all other snakes. 
Certainly in the skull they are more lizard-like than any other 
snake.

VARANIDS..

There are supposed to be bits of _Paleosaniwa_ from Hell Creek which 
indicate _V. komodoensis_ sized individuals (see Long and Welles, 
_All New Dinosaurs and Their Friends_). As monitors can hold their 
own against crocodiles and carnivorans today, I'm sure they were 
smart enough to stay away from theropods. Hey, they might even have 
been smarter than most theropods! However, there certainly were not 
any _Megalania_-sized monitors in the Mesozoic: these animals are 
Cenozoic novelties. 

Australia's giant Cenozoic reptiles (and super-abundant carpet 
pythons: more of them per area than any other terrestrial vertebrate 
carnivore apparently*) are probably something to do with Australian 
low biomass.. or so the story goes (Downund escaped Pleistocene 
glaciation, got no fertile soils, got comparatively few herbivores, 
got virtually no mammalian carnivores). This theory, nice as it is, 
has been invalidated by the large number of Australian marsupial 
carnivores described in recent years: new dasyuromorphs, carnivorous 
macropodids and thylacoleonids a-plenty.

*If you have the ref for this, I'd be real grateful.

MEGALANIA

Tom Holtz said that some workers now see this genus as a junior 
synonym of _Varanus_. This is not a new idea, but one that goes back 
to the middle of this century (see Heuvelmans 1958, for example, 
where there is much talk of _V. priscus_ [sic, I think: _V. prisca_ 
is correct]). To my knowledge, however, the reverse is true. 
_Megalania_ is now known to have unusual thickened frontal and a 
nuchal crest (see Molnar 1990, _Mem. Ql. Mus._ 29: 437-44) - it is 
odd, and is regarded by Molnar as the most derived of varanids. 
_Megalania_ neural spines also have very robust neural spines. I 
suppose these features could all be allometric, but it would also 
seem reasonable to regard them as worthy of generic status.

Coincidentally, I've actually just finished writing an article on 
tree monitors. You BCFers may be interested in the possibility that 
arboreality may be the primitive condition for some parts of the 
varanid family tree - thus explaining the arboreal youngsters of 
species nested well into certain varanid clades (e.g. _V. 
komodoensis_). Tree monitors (prasinoids) appear to be dwarfed 
hyper-derived arboreal end members of the Indo-Australian varanid 
clade.

World monitor expert (IMHO) is Robert George Sprackland. I don't 
think I ever got round to emailing him.

"It was the year of fire"
One for Tom

DARREN NAISH
darren.naish@port.ac.uk