Stick Insect Fossil Discovered in China Showed Ability to Mimic Leaves

First Posted: Mar 20, 2014 03:41 AM EDT

A team of international scientists recently unearthed fossils of the oldest known stick insect that displayed a natural ability to mimic plants in its surroundings for protection.

 Several insects develop the mechanism of mimicking the surrounding environment to protect themselves from predators. The stick insects imitate the plant leaves surrounding them but not much was known about the origin of these interactions due to lack of fossil records.

But the discovery of the fossil of this long extinct species that lived during the early Cretaceous Period some 126 million years ago offers clues concerning their unique evolution.

Researchers from France, China and Germany unearthed the fossil of the insect from the dinosaur era, dubbed Cretophasmomima melanogramma, from Inner Mongolia in Jehol. They discovered two females and one male fossil stick insects.

"Cretophasmomima melanogramma is one of the grand-cousins of 'today's stick and leaf insects," said paleontologist Olivier Bethoux of the Center for Research on Paleobiodiversity and Paleoenvironments (CR2P) and the National Museum of Natural History in Paris, one of the researchers.

"Our discovery demonstrates that plant mimicry by insects was achieved by various insect groups, including stick insects, before the rise of flowering plants," Behoux added.

The long and narrow insect fossil may have evolved this protective mechanism with the appearance of predators like birds and animals. The bugs mimicked the nearby leaves as a defensive strategy to protect themselves from tree climbing predators.

The leaf-like insect was found in a deposit from the Yixian formation in China. At this site fossils of plants, insects and dinosaurs have also been unearthed in recent years, NBC News reported.

The insect had wings with parallel dark lines. When it was in a resting position it produced a tongue like shape covering the stomach. This structure matches the fossils of a relative of the ginkgo plant collected from the same area. The leaves of this plant also had same tongue shaped leaves.

The researchers suggest that these insects used the plants as models for concealment.

"The diversification of small-sized, insect-eating birds and mammals may have triggered the acquisition of such primary defenses," say the study authors in the press release.

The finding was reported in the journal PLOS One.

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