[citation needed] In 2003 a study was published that described venom in snake subfamilies previously thought to lack it.

[11][12] As a practical matter, Fry cautioned:[13] Some non-venomous snakes have been previously thought to have only mild 'toxic saliva'.

[2] It is thought that this was the result of descent from a common venom-producing squamate ancestor; the hypothesis was described simply as the "venom clade" when first proposed to the scientific community.

[2] The venoms are thought to have evolved after genes normally active in various parts of the body duplicated and the copies found new use in the salivary glands.

[2] Previously known venomous squamates have already provided the basis for medications such as Ancrod, Captopril, Eptifibatide, Exenatide and Tirofiban.

[15] Other scientists such as Washington State University biologist Kenneth V. Kardong and toxicologists Scott A. Weinstein and Tamara L. Smith, have stated that the allegation of venom glands found in many of these animals "has had the effect of underestimating the variety of complex roles played by oral secretions in the biology of reptiles, produced a very narrow view of oral secretions and resulted in misinterpretation of reptilian evolution".

According to these scientists "reptilian oral secretions contribute to many biological roles other than to quickly dispatch prey".