diacranterian

from The Century Dictionary.

• Having teeth in rows separated by an interval: applied to the dentition of serpents in which the posterior teeth are separated by a considerable interval from the anterior: opposed to syncranterian. Also dicranterian.
• Having a tooth in the hinder portion of the jaw longer than the other teeth. This type of dentition is found in some snakes, the common hog-nosed viper, Heterodon, being a good example: opposed to isodont.
• noun A snake having a tooth in the hinder part of the jaw longer than the other teeth.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective herpetology Having the back teeth separated from the front teeth.