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For example , scientists working on cone snails , venomous predatory gastropods , have found a pattern of gene duplications , followed by rapid evolution of exons . Natural history museum collections ( preserved and cataloged plant and animal specimens ) provide some of the most detailed information about the distribution of organisms in space and time . The frequent gene duplications provide additional venom proteins , expanding the snake 's arsenal and increasing the chance that the prey will be killed . The lower jaw , or mandible , consists of two bones that meet at the chin but easily separate in the process of decay . A rattler he was raising in a biology laboratory gave birth to 17 snakelets . They are small in stature and , where known , hang beneath glue-sticky silk sheet webs .