 Based on molecular clock estimation , Trigonognathus is thought to have originated around 41 million years ago during the Middle Eocene , as part of a larger evolutionary radiation of <unk> genera . The genus is represented in this time period by the extinct species T. <unk> , whose fossilized teeth have been recovered from Lutetian age ( 47 @.@ 8 – 41 @.@ 3 Mya ) strata in Landes , southwestern France . Fossil teeth virtually identical to those of the modern viper dogfish are known from the Cubagua Formation in northeastern Venezuela , which dates to the Late Miocene and Early Pliocene ( 11 @.@ 6 – 3 @.@ 6 Mya ) . 
