A New Cretaceous Insect with a Unique Cephalo-thoracic Scissor Device.

Insects use different parts of their body to cling to mating partners, to catch prey, or to defend themselves, in most cases the mouthparts or the legs. However, in 400 million years of evolution [1, 2], specialized devices were independently acquired in several groups to adopt these tasks, as for instance modified legs in mantids, assassin bugs or stick insects [3-5], or clasping antennae of the globular springtails [6]. So far, no known species used the neck region between the head and thorax in one of these functional contexts. Here we describe females of †Caputoraptor elegans, a very unusual, presumably predacious insect discovered in approximately 100-million-year-old [7] Burmese amber. Based on several morphological features, we conclude that this species lived in the foliage of trees or bushes. A unique feature of the new taxon is a scissor-like mechanism formed by wing-like extensions on the posterior head and corresponding serrated edges of the dorsal sclerite of the first thoracic segment. Based on the specific structure of the apparatus, we conclude that it was probably used by females to hold on to males during copulation. A defensive or prey-catching function appears less likely. A similar mechanism did not evolve in any other known known group of extant or extinct insects.