Scientists have studied two species of sand lizards, the Mojave fringetoed lizard and the western zebratailed lizard, to understand the extent to which the different structure of the two species' toes is related to their preferred habitatsfine sand for the Mojave lizard and coarse sand for the zebratailed lizard. (Figure 1) shows a somewhat simplified velocityversustime graph for the Mojave fringetoed lizard.