Hi mate



>>Relative to elapids and pitvipers, they do not have the adaptations for injecting venom deep into tissue.



Of course not. Highly developed fangs were an additional improvement that came after the evolution of venom, and such fangs have evolved at least four times on separate occasions. The enlarged teeth were an improvement over normal teeth and facilitate the venom by creating deeper wounds. Grooving was a subsequent improvement to help channel the venom and hollow hypodermic needle fangs the ultimate adaptation.



Evolution of the venomous snakes could be viewed as:



1. Venom - the obvious first step and happened only one time (which is why the term 'Duvernoy's gland' to distinguish 'colubrid' venom glands from elapid or viper homologs, has been abandoned and venom gland used in all cases).

2. Enlarged teeth - quite variable as to which and evolving on quite a number of occasions, this is why aglyph and opisthoglyph are artificial distinctions that shoe-horn a unrelated snakes into entirely contrived distinctions.

3. Grooved teeth - yet again quite variable and independently evolving on numerous occassions.

4. Hollow fangs - variable yet again. The elapid fangs are unrelated to the viper fangs and the Atractaspidae fangs appear to be a third evolution. The highly mobile and extremely advanced boomslang fangs, while not hollow are deeply grooved and represent a fourth evolution of advanced architecture.





> The paper I cited made a pretty good case for the enlarged teeth being used primarily for holding struggling live prey.



The paper you are referring to was written before the relationship of the venoms of the various 'colubrid' families in relation to the atractaspids/elapids/viperids was worked out. This is not to say that large teeth are not useful in holding prey but they are more likely to be enlarged ones in the front of the mouth rather than tucked all the way in the back (ie the large front teeth in Ahaetulla species).



Cheers

Bryan
-----
Dr. Bryan Grieg Fry

Deputy Director

Australian Venom Research Unit

University of Melbourne



www.venomdoc.com

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