To escape prying predators, fragile fauna often become masters of the art of disguise. Take the leaf insects of Southeast Asia: They so strongly resemble leaves that they blend in with the surrounding foliage. Because the 37 species of leaf insect now live in one corner of the planet, entomologists had assumed that their camouflage was a relatively recent adaptation.
In January 2007, however, researchers announced the discovery of the first fossil leaf insect: a well-preserved, 47-million-year-old specimen from Messel, Germany. Named Eophyllium messelensis, the insect looks almost identical to its modern relatives, indicating the group is ancient, was once widespread, and has hardly changed in millions of years.
Biologist Sonja Wedmann, then at the Institute of Paleontology at the University of Bonn, analyzed the fossil after it was dug up from oil shale deposits in what was once a small lake formed by volcanic activity. The period when the insect lived, the Eocene, was one of the warmest in history, and lush tropical or subtropical rain forest surrounded the lake; the two-and-a-half-inch-long adult male most likely sat and snacked upon the leaves of plants from the laurel or the pea family.
So complete is the fossil—its head, antennae, thorax, wings, legs, and leaf-shaped abdomen intact—that it provides key clues on how it hid from predatory birds and primates: Its curved forelegs form a notch into which the insect could tuck its head. “We can infer that the fossil leaf insect showed the same behavior as extant leaf insects do,” Wedmann says. “It is hiding its head between the legs and sitting still on the leaf during the day, and when it is disturbed, it rocks from side to side like a leaf.”
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