Grooves to tubes: evolution of the venom delivery system in a Late Triassic “reptile”

So this article is about attempting to follow the evolutionary history of the highly specialized teeth found in many venomous snakes that we see today. As was discussed in class the actual evolutionary origin of these specialized structures is not completely known. This article suggests that there is an infolding pattern in the grooved teeth over time that eventually resulted in the hollow fangs we see today in many of the pit vipers. The problem with this is that the fossils of snake skulls that are found all have the same features their extant descendants exhibit in fang morphology. This is probably due to snake skulls not preserving very well due to the inherit weakness their skulls have due to the range of motion snakes can produce in the skulls. However this article claims to have found a late Triassic reptile (not snake) known as Uatchitodon schneideri that supports this hypothesis. They claim that teeth belonging to these reptiles show a progression from a shallow groove like fang, all the way to the hollow tubes found in the pit vipers of today. The procedure essentially consists of the researchers examining these teeth with a scanning electron microscope, taking pictures of the images, and then manipulating these images in Photoshop to enhance the contrast in order to verify morphology. By doing this the researchers were able to confirm the infolding hypothesis as a viable to form hollow fangs in at least one evolutionary pathway.

     This article sheds some light on the evolutionary beginnings of these complex venom delivery systems in squamates. This article is by Jonathan S. Mitchell, Andrew B. Heckert, & Hans-Dieter Sues and can be found in the journal Naturwissenschaften. That name is a bit of a mouth full so here is a link.

http://www.springerlink.com.nuncio.cofc.edu/content/p80x852127v71k48/fulltext.pdf