Reptile & Amphibian Forums

Can anybody tell me how closely related these two are, or recommend any good literature on the subject? In 'Venomous reptiles of North America', Carl H. Ernst, it just states that "The family is closey related to the Old World monitor lizard family Varanidae". I am interested in approximately when, and how, the split in the family tree occured.

On a side note, are there any differences in the evoltuion of Australian varanids and African/Asian?
Thanks.
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Pozdrav,
Anton T.
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1.1 Python regius
0.1 Boa constricor imperator
0.1 Elaphe g. guttata
1.0 Lampropeltis t hondurensis
0.2 Varanus exanthematicus
0.1 Crotaphytus collaris
0.1 Testudo horsefieldi
1.4 Anolis carolinensis
1.0 Tarentola mauretanica
0.2 Pachydactylus bibronii
1.0 Litoria caerulea

Hi Anton,

Gilas and varanus are included within the same subfamily, Varanoidea, which includes living/extinct varanus, living/extinct helodermids, and Earless Monitor. Dr. Gilmore's 1928 treatise on the fossil saurians of North America describes it well; Jennifer Ast did a recent paper on relationships in the Varanidae (Journal of Cladistics, 2002) or Michael Lee of varanoid lizards and the affinities of snakes (Philosophical Transactions Royal Society London 1997, 352:53-91).

Can you tell me more about the book you cited?

Cheers,
markb

Hey, thanks for the info...any help obtaining those sources? Unfortunately I cannot find those texts at my local library (I live in a rural area).
As far as the book is concerned, It is called "Venomous reptiles of North America), author Carl H. Ernst,Smithsonian Institution Press, 1992.
I consider it a very good book, since I deal primarily with venomous snakes, and it contains info on EVERY native North American species.
As far as the gila/varanid relation goes, I was just wondering because I am trying to find more info on WHY gilas/beadeds developed a venom apparatus, how it evolved, and why don't any of the varanids have it. From what I've read, they do not use venom to kill/subdue their prey, since it is ingested in the typical varanid fashion. That leads me to believe that it is more of a protective device, and since they do not have that many natural predators (humans being the worst), from my research less than your typical varanid, how come any of the varanids don't have a similar venom apparatus.
Pozdrav,

Anton T.
P.S. I just love the report of one attacking an automobile door, and chewing (and trying to inject venom) on the door handle for 15 minutes