Twig mimicry is most common and diversified in Phasmatodea (stick and leaf insects), a group of iconic models for understanding the evolution of camouflage and mimicry among insects. Extant stick and leaf insects exhibit a wide array of exaggerated morphologies mimicking twigs, bark, fresh or dried leaves, ferns, and even moss. However, the fossil record of Phasmatodea is relatively sparse, and the most ancient stick insects from 100 million years ago lack obvious characteristics relating to the familiar twig mimicry of the extant groups.
Click here for original story, The early evolution of successful twig mimicry in insects
Source: Phys.org