Editing Snake skeleton (section)

====Opisthoglyph====
[[Image:Heterodon nasicus skull.jpg|thumb|left|An '''opisthoglyphous''' snake. A [[hognose snake]] skull (''[[Heterodon nasicus]]'')]]'''Opisthoglyphous''' ("rearward grooves") snakes possess venom injected by a pair of enlarged teeth at the back of the [[maxillae]], which normally angle backward and are grooved to channel venom into the puncture. Since these fangs are not located at the front of the mouth, this arrangement is [[Vernacular|vernacularly]] called "rear-fanged".  In order to envenomate prey, an opisthoglyphous snake must move the prey into the rear of its mouth and then penetrate it with its fangs, presenting difficulties with large prey although they can quickly move smaller prey into position. The opisthoglyphous dentition appears at least two times in the history of snakes.<ref>Bruna Azara, C. (1995). "''Animales venenosos. Vertebrados terrestres venenosos peligrosos para el ser humano en España'' ". ''Bol. SEA'' '''11''': 32-40.</ref> The venom of some opisthoglyphous snakes is strong enough to harm humans; notably, [[herpetologist]]s [[Karl Patterson Schmidt|Karl Schmidt]] and [[Robert Mertens]] were killed by a [[boomslang]] and a [[twig snake]], respectively,<ref>As herpetologists, both kept a record of the effect up to their death, Schmidt for a couple of days: https://people.wku.edu/charles.smith/chronob/SCHM1890.htm</ref><ref>Mertens kept a diary of his dying for full 18 days: cf Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiiiISBN 978-1-4214-0135-5. ("Mertens", p. 176; "Robert", p. 223; "Robert Mertens", p. 223).</ref> after each underestimated the effects of the bite and failed to seek medical help. Opisthoglyphous snakes are found mostly in the families [[Colubridae]] and [[Homalopsidae]]. {{clear}}